A list of all our privacy-preserving, lightweight browser-based tools. All tools run directly in your browser without uploading any data to our servers.
| Tool Name | Description | Category | Link |
|---|---|---|---|
| .htaccess Redirect Generator & RewriteRule Tester | Generate single or bulk Apache redirects, test existing .htaccess rules, detect chains and loops, and download a ready-to-use file free in your browser. | web | Open tool |
| 2D Rotation Matrix Calculator | Generate an exact 2×2 matrix, rotate points or vectors around any pivot, and find an angle from a matrix. Accepts degrees, radians, pi expressions, and batch coordinates. | linear-algebra | Open tool |
| 3D Distance Calculator | Calculate the straight-line distance between two 3D points. Enter x, y, z coordinates, see the formula, and get a step-by-step solution instantly. | geometry | Open tool |
| 401(k) Calculator | Project your 401(k) balance with salary growth, employee deferrals, employer match, IRS contribution limits, inflation, and retirement withdrawals. Runs locally in your browser. | finance | Open tool |
| 50/30/20 Budget Calculator and Planner | Use this 50/30/20 budget calculator and planner to split take-home income by frequency, compare expenses, and see needs, wants, and saving/debt guidance. | finance | Open tool |
| 50/50 AMM Impermanent Loss Calculator | Calculate impermanent loss for Uniswap-style 50/50 AMM liquidity pools. Compare LP value, HODL value, token amounts, fees, rewards, and break-even offsets. | finance | Open tool |
| A/B Redundant Power and Failover Capacity Calculator | Audit A/B rack power redundancy, 2N capacity, active/active and active/passive PSU behavior, ATS transfer, reserves, and surviving-feed utilization. | infrastructure | Open tool |
| Absolute Value Equation and Inequality Calculator | Enter an absolute value equation or inequality such as |2x-3|=5. Get exact roots, detailed algebra steps, interval and set-builder notation, a number line, and a graph. | algebra | Open tool |
| AC Power Calculator – Watts, Amps, kW, kVA and Power Factor | Calculate AC power from volts, amps, and power factor. Supports single-phase and three-phase circuits, watts, kW, kVA, kVAR, amps conversion, and energy cost estimates. | calculators | Open tool |
| Acceleration Conversion Calculator | Convert acceleration between m/s², g (Earth g), ft/s², in/s², Gal, mGal, µGal, km/h/s, mph/s, and knot/s. Instant, accurate, private (client-side). | science | Open tool |
| Accounting Rate of Return (ARR) Calculator | Free Accounting Rate of Return (ARR) calculator. Simple or detailed. Compute ARR using average accounting profit and initial or average investment. 100% client-side. | finance | Open tool |
| Acid–Base Titration Calculator | Calculate unknown molarity, required titrant volume, equivalence point, pH, and an interactive acid-base titration curve with coefficients, steps, and indicator guidance. | science | Open tool |
| Acoustic Impedance Calculator – Z = ρc, MRayl, Reflection & Transmission | Calculate specific acoustic impedance z = ρc in Rayl and MRayl, then compare two materials for reflection, transmission, return loss, and quarter-wave matching. | science | Open tool |
| Acoustic Treatment Calculator: How Many Panels? | Calculate how many acoustic panels and bass-trap modules your room needs, then get an ordered placement plan, first-reflection coordinates, RT60 estimate, costs, and printable diagrams. | studio | Open tool |
| Acres to Square Feet Calculator | Convert acres to square feet instantly. Includes square yards, square meters, hectares, copy, CSV download, and clear formula notes. Private and client-side. | calculators | Open tool |
| Add Page Numbers to PDF Online – Free, Private Tool | Add page numbers to one or more PDFs free in your browser. Files stay on your device; choose ranges, formats, placement, and advanced Bates numbering. | documents | Open tool |
| Add Text to Image Online Free | Add text to an image online for free. No signup or watermark: use movable text layers and export PNG, JPEG, or WebP at the dimensions you choose. | graphics | Open tool |
| Add Watermark to Image Online Free – Text or Logo | Add a text or logo watermark to one image or a batch for free. No signup, no uploads, full-resolution local processing, presets, and ZIP export. | graphics | Open tool |
| Adjacency Matrix Generator & Calculator | Generate, edit, analyze, and visualize binary or weighted adjacency matrices. Convert edge lists, adjacency lists, and matrices for directed or undirected graphs. | discrete-mathematics | Open tool |
| Advanced Redshift and Cosmology Calculator | Advanced adjustable FLRW cosmology calculator for redshift, luminosity and comoving distance, cosmic age, lookback time, curvature, angular scale, and batch CSV results. | science | Open tool |
| Age Calculator — Years, Months & Days | Free Age Calculator: get exact age in years, months, and days, see time until your next birthday, or calculate age on any specific date. | time-date | Open tool |
| Age Difference Calculator | Age Difference Calculator: compare dates of birth, current ages, birth years, or any two dates. Get exact age gaps in years, months, days, weeks, and total days. | time-date | Open tool |
| Age in Weeks and Months Calculator | Calculate age in weeks, months, and days from a date of birth. Baby-friendly age calculator with calendar months, decimal months, total days, and optional target date. | time-date | Open tool |
| Age on Other Planets Calculator | Calculate how old you are on Mars, Mercury, Venus, Jupiter, Saturn, Uranus, Neptune, and Pluto, with planetary birthdays and orbit progress. | fun | Open tool |
| Air Conditioner BTU Calculator: What Size AC Do I Need? | Free air conditioner BTU calculator: estimate room AC size, nearest common BTU/h unit, and tons from room size, sunlight, people, insulation, room type, and climate. | construction | Open tool |
| Air Fryer Calculator: Convert Oven Time & Temperature | Free oven to air fryer calculator and conversion chart. Convert oven temperature and cooking time to air fryer settings, with presets for fries, chicken, vegetables, frozen snacks, basket load, and crispness. | cooking | Open tool |
| Alternator Size Calculator: What Size Alternator Do I Need? | Check alternator sufficiency at hot idle or cruise. Estimate car audio and vehicle electrical loads with editable presets, accessory lists, and reserve. | automotive | Open tool |
| Amortization Calculator with Schedule & Extra Payments | Calculate loan payments, amortization schedules, interest saved, and payoff time saved with optional extra principal payments. Runs 100% in your browser. | finance | Open tool |
| Anamorphic Squeeze & Desqueeze Calculator | Calculate anamorphic aspect ratio, desqueezed resolution, crop and timeline scaling. Plan from pixels or recording shape, including vertical delivery. | studio | Open tool |
| Anchor Scope Calculator – Rode Length & Swing Circle | Calculate anchor scope or rode length from depth, tide and bow height. See rounded payout marks, scope comparisons and an estimated swing circle. | marine | Open tool |
| Angle Between Two Vectors Calculator | Calculate the angle between two 2D, 3D, or 4D vectors in degrees and radians. Shows dot product, magnitudes, cosine similarity, and step-by-step work. | linear-algebra | Open tool |
| Annuity & Break-Even Calculator | Calculate annuity present value and future value, then check break-even units, revenue, margin and markup. Includes ordinary, due and growing annuity formulas. | finance | Open tool |
| Annulus Calculator — Ring Area, Circumference and Radii | Calculate annulus area, inner and outer radii, ring width, diameters, and both circumferences from any two independent measurements. | geometry | Open tool |
| Ant Colony Simulator Online: Pheromone Trails, Food Paths & Swarm Intelligence | Free online ant colony simulator showing pheromone trails, food paths, evaporation, diffusion, obstacles, and swarm intelligence. Run an interactive agent-based model in your browser. | science | Open tool |
| Antifouling Bottom Paint Calculator – Coverage, Coats & Cans | Estimate boat bottom area, antifouling paint per coat, total volume, and whole cans from dimensions or measured area, coverage, coats, waste, and can size. | marine | Open tool |
| AOE Calculator — Any Time on Earth (UTC−12) | AOE (Any Time on Earth) is the UTC−12 deadline convention used by conferences and journals — the last moment it is still that date anywhere on Earth. Convert AOE deadlines to your local time, with DST-safe output, countdown timer, and .ics calendar export. | time-date | Open tool |
| Apparent Wind Calculator | Calculate apparent wind speed and angle from true wind speed, true wind angle, and boat speed, with knots, mph, km/h, and m/s conversions. | marine | Open tool |
| Apple Cocoa / Core Data Time Converter — CFAbsoluteTime ↔ Date | Convert Apple Cocoa, Core Data, and Mac absolute time values since 2001-01-01 UTC to dates and back. Handles CFAbsoluteTime, NSTimeInterval, fractional seconds, and nanosecond timestamps. | time-date | Open tool |
| APR to APY Calculator | Convert APR to APY or APY to APR by compounding frequency: monthly, quarterly, daily 360/365, custom, or continuous. Includes formulas and examples. | finance | Open tool |
| AQI to PM2.5 Converter (US EPA) | Convert U.S. EPA PM2.5 AQI to PM2.5 concentration or PM2.5 to AQI, with calculation steps, possible ranges, health guidance, and 2024 breakpoints. | environment | Open tool |
| Arc Length Calculator — Circle, Function, Parametric & Polar Curves | Calculate circular, function, parametric and polar arc lengths with exact answers for recognized cases, numerical integration, steps, symbolic bounds and graphs. | calculus | Open tool |
| Arithmetic or Geometric Sequence Calculator — Nth Term & Sum | Solve arithmetic or geometric sequences from terms, positions, differences, ratios, or sums. Supports exact fractions, infinite sums, tables, graphs, and worked steps. | algebra | Open tool |
| Army Body Fat Calculator: Current 2026 WHtR Standard | Check the current 2026 U.S. Army body composition standard using waist-to-height ratio. Applies the official 0.550 cutoff and three-decimal truncation rule. | health | Open tool |
| Aspect Ratio Calculator — Pixel dimensions for video, photos & monitors | Calculate width or height from any aspect ratio instantly. Includes presets for video, social media, photography, print, ultrawide monitors, and gaming. | studio | Open tool |
| Asphalt Calculator: Estimate Tons, Volume, Cost, and Sealer | Estimate asphalt tons, volume, cost, truckloads, waste, and sealer buckets. Includes hot mix, warm mix, cold mix, porous, and recycled asphalt options. | construction | Open tool |
| Astronomical Unit Converter and Astronomical Distance Converter | Astronomical distance converter for AU to km, light-years to km, parsecs to light-years, kpc, Mpc, Gpc, miles, light-time units, and common astronomy distances. | science | Open tool |
| Audio Bit Depth Calculator — Dynamic Range, Quantization Levels & Noise Floor | Calculate audio quantization levels, ideal sine-wave dynamic range, one-LSB range, quantization noise floor, and signal SQNR for any integer bit depth. | studio | Open tool |
| Audio Crossover Calculator — Frequency, Slopes & Component Values | Calculate passive 2-way speaker crossover capacitor and inductor values for 6, 12, or 18 dB/octave Butterworth and Linkwitz–Riley filters. | studio | Open tool |
| Audio File Size Calculator — WAV, MP3, AAC, FLAC and Recording Time | Calculate audio file size for WAV, AIFF, MP3, AAC, FLAC, and PCM recordings. Estimate MB/GB from sample rate, bit depth, channels, bitrate, duration, or storage size — all client-side. | studio | Open tool |
| Audio Latency Calculator — Buffer Size, Sample Rate & Round-Trip Delay | Calculate audio input, output, and round-trip latency from buffer size and sample rate. Add measured driver or converter overhead and compare common settings. | studio | Open tool |
| Audio Sample Rate Calculator | Calculate Nyquist frequency, dynamic range, bitrate, and uncompressed audio file size. Compare 44.1, 48, 96, and 192 kHz sample rates for recording, mixing, video, and delivery. | studio | Open tool |
| Auto Loan Calculator with Tax, Trade-In, APR & Amortization | Estimate your monthly car payment with vehicle price, down payment, trade-in, amount owed, sales tax, fees, APR, and term. See total interest, payoff date, and amortization schedule. | finance | Open tool |
| Average (Mean) Calculator | Free average calculator for numbers separated by commas, spaces, tabs, or new lines. Get the arithmetic mean, sum, count, min, max, range, and calculation steps. | statistics-probability | Open tool |
| Backup WAN Link Sizing Calculator | Calculate required backup WAN download and upload speeds for failover, including SD-WAN or VPN overhead, QoS priorities, traffic shedding, headroom, growth, and metered data. | infrastructure | Open tool |
| Backup Window Calculator for Backup Duration, Throughput, and Storage | Estimate backup duration, required throughput, full vs incremental backup time, compression, deduplication, retention storage, and whether your backup fits your target window. | infrastructure | Open tool |
| Baker's Percentage Calculator for Bread, Pizza & Sourdough Hydration | Calculate baker's percentages, dough hydration, salt, yeast, starter, and total dough weight for bread, pizza, and sourdough. Scale by flour weight or final dough weight. | cooking | Open tool |
| Balance Transfer Calculator | Compare a credit card balance transfer with keeping your current card. Estimate transfer fees, promotional and post-promo interest, payoff time, break-even point, and net savings. | finance | Open tool |
| Baluster and Spindle Spacing Calculator | Find baluster count, clear gap, on-center spacing, end margins, and layout marks for deck or stair railings. Includes 4-inch/100 mm code guidance. | construction | Open tool |
| Bandwidth Calculator for File Transfer Time and Required Speed | Calculate file transfer time, required bandwidth, effective throughput, and data moved per day or month. Supports Mbps, Gbps, MB/s, GB, TB, overhead, and efficiency. Private, client-side. | infrastructure | Open tool |
| Basal Metabolic Rate (BMR) Calculator | Estimate your BMR and daily calorie needs with Mifflin–St Jeor, Harris–Benedict, Katch–McArdle, and Schofield formulas. Includes metric/US units, formula steps, activity multipliers, limitations, and privacy-first client-side calculations. | health | Open tool |
| Baseboard Calculator: Linear Feet, Boards and Cost | Use this baseboard calculator to estimate linear feet, full boards, waste, rounding surplus, and cost, with optional room-by-room casing and shoe molding takeoffs. | construction | Open tool |
| Battery Reserve Capacity to Amp Hours Calculator (RC ↔ Ah and Runtime) | Convert battery reserve capacity to amp hours or Ah to RC instantly. Estimate runtime and accessory load with optional Peukert ranges and clear planning factors. | automotive | Open tool |
| Battery Runtime Calculator | Calculate how long a 12V, 24V, 48V or UPS-style battery will run from Ah, Wh, voltage, load watts, depth of discharge, efficiency and battery age. Includes formula, examples and required Ah sizing. | infrastructure | Open tool |
| Bayes’ Theorem Calculator — Prior, Likelihood & Posterior Probability | Calculate posterior probability from a prior and likelihood. Use a false-positive rate or evidence probability, with Bayes’ theorem steps, odds, and validation. | statistics-probability | Open tool |
| BBQ Meat Calculator | Calculate BBQ meat per person, raw shopping weight, cooked yield, cooking time, and when to start. Supports brisket, ribs, pulled pork, chicken, burgers, steak, and sausages. | cooking | Open tool |
| Beer–Lambert Law Calculator (A = εlc) | Friendly Beer–Lambert calculator. Solve absorbance (A), molar absorptivity (ε), path length (l), or concentration (c). Optional %T input. 100% client-side and private. | science | Open tool |
| Bellows Exposure Compensation Calculator | Calculate bellows extension factor, added exposure stops, effective aperture, corrected shutter time, aperture, and ISO from focal length and total bellows draw. | studio | Open tool |
| BGP Prefix Aggregation Calculator | Aggregate IPv4 and IPv6 CIDR prefixes, remove contained routes, calculate exact summaries, compare covering prefixes, and count BGP route reduction. | infrastructure | Open tool |
| Bilge Pump Capacity Calculator | Estimate bilge pump capacity from inflow, timed water accumulation, or measured bilge rise. Adjust for clearing time, reserve, and installed pump output. | marine | Open tool |
| Binary Relation Properties Calculator | Check whether a finite binary relation is reflexive, symmetric, transitive, antisymmetric, or irreflexive. See counterexamples, classifications, and closures. | discrete-mathematics | Open tool |
| Bingo Card Generator — Printable Cards, PDF Pack, Caller Sheet | Generate 1 to 30 printable bingo cards with classic 1–75, 1–90, 1–100, custom ranges, custom words, free space controls, PNG export, and a printable caller sheet. | random | Open tool |
| Binomial & Poisson Distribution Calculator | Calculate binomial and Poisson probabilities: P(X=k), P(X≤k), P(X≥k), between values, mean, variance, standard deviation, PMF/CDF table and chart. | statistics-probability | Open tool |
| BioStats Quick Calculator — Welch's t-test, Chi-square, One-way ANOVA | Run Welch's t-test, Student's t-test, chi-square (χ²), and one-way ANOVA in your browser. Get p-values, confidence intervals, effect sizes, summaries, and CSV export. | science | Open tool |
| Bipartite Graph Checker and Two-Coloring Visualizer | Check whether an undirected graph is bipartite. Get a valid two-coloring and partitions, or find and visualize an odd cycle that proves it is not bipartite. | discrete-mathematics | Open tool |
| Birthday Countdown Calculator | Birthday Countdown Calculator: find how many days, hours, minutes, and seconds until your next birthday, the date, weekday, and age you will turn. | time-date | Open tool |
| Birthday Paradox Calculator — Probability of Shared Birthdays | Birthday Paradox Calculator: find the chance that at least two people in a group share a birthday. Choose group size, toggle leap day, and see odds. | time-date | Open tool |
| Bitcoin Mining Profitability Calculator | Estimate Bitcoin mining profit with live BTC network defaults, ASIC presets, electricity scenarios, profit per watt, breakeven price, and ROI. | finance | Open tool |
| Bitcoin Transaction Fee Calculator | Estimate Bitcoin transaction size from inputs and outputs, compare live sat/vB priorities, and calculate fees in sats, BTC, and fiat. | finance | Open tool |
| Bitcoin Unit Converter: BTC to Satoshis, Sats to BTC, mBTC & Bits | Convert BTC, satoshis/sats, mBTC and bits instantly. Includes formulas, common conversion tables and exact BTC ↔ sats math. Private, in-browser, no price API. | finance | Open tool |
| Blackbody Radiation Calculator | Calculate blackbody peak wavelength, Planck spectral radiance, emitted flux and total power from temperature, emissivity, wavelength and area. Includes spectrum graph, examples and unit tables. | science | Open tool |
| Bloch Sphere Simulator: Visualize a Qubit State | Interactive Bloch sphere simulator for a single qubit. Explore quantum superposition with gates, measurements, amplitudes, mixed states, formulas and exports. | science | Open tool |
| Blood Pressure Calculator: Check Your BP Category | Enter systolic and diastolic blood pressure to check your BP category using ACC/AHA 2025 and NICE NG136 thresholds, with single-reading and average-reading guidance. | health | Open tool |
| BMI Calculator - Body Mass Index and Healthy Weight Range | Calculate BMI instantly in metric or US units. See adult BMI category, obesity class, healthy weight range, and BMI context with private client-side calculations. | health | Open tool |
| BMI vs Body Fat Calculator: Compare BMI and Body Fat % | Calculate BMI and body fat percentage, compare Deurenberg and US Navy estimates, understand disagreements, and see fat mass, lean mass, ranges, and categories. | health | Open tool |
| Boat Battery Bank and Runtime Calculator | Calculate boat battery bank voltage, amp-hours, usable energy, runtime, and required capacity from series-parallel wiring, load, state of charge, health, efficiency, and Peukert effect. | marine | Open tool |
| Boat Displacement and Load Capacity Calculator | Calculate loaded boat displacement, remaining load capacity, capacity used, weight breakdown, and displaced water volume in pounds or kilograms. | marine | Open tool |
| Boat Draft and Under-Keel Clearance Calculator | Calculate boat draft clearance from depth and tide, then adjust under-keel clearance for squat, heel, motion, uncertainty, and a selected minimum margin. | marine | Open tool |
| Boat Engine Horsepower and Power-to-Weight Calculator | Calculate total boat engine horsepower and power-to-weight ratio in hp per 1,000 lb, hp per ton, kW per tonne, W/kg, lb/hp and kg/kW. | marine | Open tool |
| Boat Freshwater Tank Duration Calculator | Estimate how many days a boat freshwater tank will last from tank level, reserve, crew size, per-person use, shared daily use, and optional trip duration. | marine | Open tool |
| Boat Fuel Consumption Calculator | Calculate boat fuel consumption, GPH or L/h, trip fuel, reserve, cost, tank endurance and cruising range from distance, speed, engines and fuel burn. | marine | Open tool |
| Boat Loan Calculator with Taxes, Fees, APR & Amortization | Estimate boat loan payments with price, down payment, trade-in, taxes, marine fees, APR, term, extra payments, payoff date, and amortization schedule. Private, client-side calculator. | finance | Open tool |
| Boat Loan Payoff and Ownership Cost Calculator | Estimate a boat loan payoff date, remaining interest, extra-payment savings, annual ownership cost, fuel cost, and projected cash outlay with a private browser calculator. | marine | Open tool |
| Boat Planing Speed and Froude Number Calculator | Calculate a boat's length Froude number and speed at a selected planing comparison value from waterline length. Supports knots, mph, km/h, m/s, feet, and meters. | marine | Open tool |
| Boat Propeller Pitch and Slip Calculator | Calculate boat propeller slip, theoretical or actual speed, required pitch, engine RPM, or gear ratio. Supports mph, knots, km/h, clear formulas, and local-only inputs. | marine | Open tool |
| Boat Range and Reserve Fuel Calculator | Calculate boat range, endurance, reserve fuel, out-and-back distance, and trip fuel margin from usable fuel, cruise burn, speed, and reserve policy. | marine | Open tool |
| Boat Shore Power Load Calculator – Amps, Watts & Circuit Capacity | Calculate boat shore power amps, watts, volt-amps, per-leg load, and remaining 30A, 50A, 16A, or 32A circuit capacity with power factor. | marine | Open tool |
| Boat Trailer Weight and Towing Capacity Calculator | Calculate loaded boat trailer weight and tongue weight, then check tow rating, vehicle payload, GCWR, hitch limit and trailer GVWR in pounds or kilograms. | marine | Open tool |
| Boat Trim and Weight Distribution Calculator | Calculate loaded boat longitudinal center of gravity, fore-and-aft load distribution, corrective weight shift, trimming moment, and optional trim change. | marine | Open tool |
| Body Surface Area Calculator — Mosteller, Du Bois and Haycock | Calculate body surface area (BSA) from height and weight with Mosteller, Du Bois, and Haycock formulas. Compare results in m² using metric or US units. | health | Open tool |
| Bond Price & Yield Calculator | Calculate bond price, yield to maturity, current yield, clean price, dirty price, accrued interest, coupon payments, duration, convexity, and cash flows. | finance | Open tool |
| Boolean Algebra Simplifier with Truth Table | Simplify Boolean expressions into reduced SOP and POS forms, generate a complete truth table, and copy or download results. Free, private, and client-side. | discrete-mathematics | Open tool |
| Box Packing Calculator: How Many Boxes Do I Need? | Calculate how many boxes you need from item and internal box dimensions, usable capacity, physical fit, weight limits, fill rate and unused volume. | logistics | Open tool |
| BPM to Delay Time Calculator – BPM to ms, Hz, Dotted & Triplet Notes | Free BPM to delay calculator for music producers, guitarists and mixers. Convert tempo to milliseconds, Hz, dotted notes, triplets, reverb pre-delay and LFO rates. | studio | Open tool |
| Brake Bias Calculator: Actual vs Ideal Front/Rear Bias | Calculate brake bias from caliper pistons, rotor size, pressure ratio, and tire size, then compare actual front/rear brake balance with ideal bias from weight transfer. | automotive | Open tool |
| Brake Pad Life Calculator: Miles and Percentage Remaining | Calculate usable brake pad percentage, miles or kilometres left, observed thickness wear rate, months remaining, and a replacement-planning date. Includes a mileage-only estimator. | automotive | Open tool |
| Breadth-First and Depth-First Search Graph Visualizer | Visualize breadth-first search and depth-first search step by step. Compare traversal order, queue or stack state, parent trees, and vertex depths. | discrete-mathematics | Open tool |
| Brick and Mortar Calculator | Estimate bricks, blocks, mortar, sand, cement, openings, waste, and project cost from wall length and height. Includes UK metric and US imperial assumptions. | construction | Open tool |
| Brine Calculator | Calculate salt for wet brines, dry brines, turkey, chicken, pork, seafood, and pickles. Includes salt percentages, kosher salt conversions, timing charts, and examples. | cooking | Open tool |
| Buffer pH Calculator — Henderson–Hasselbalch Equation | Calculate buffer pH, pKa or pKb, component ratio, missing concentration, recipes, and strong acid/base stress for acid or base buffers. | science | Open tool |
| Buoyancy Calculator - Archimedes Principle, Buoyant Force, Float or Sink | Calculate buoyant force, displaced volume, object density, apparent weight, float or sink status, submerged fraction, and boat or barge draft with flexible units. | science | Open tool |
| Business Days Calculator | Free business days calculator to count workdays between two dates or add/subtract business days from a start date. Exclude weekends, holidays, and custom dates. | time-date | Open tool |
| Business Days Calculator: Count Workdays Between Dates | Count business days between dates or add and subtract workdays. Set any workweek and exclude automatic public holidays or custom closure dates. | time-date | Open tool |
| Business Loan Calculator – Payments, APR and Amortization Schedule | Calculate business loan payments, estimated fee-inclusive APR, total interest, payoff date, balloon payment, and a downloadable amortization schedule. | finance | Open tool |
| Cable Tray Fill Calculator: Fill Percentage, Capacity, Tray Size & NEC 392 Screening | Calculate installed cable tray fill, remaining capacity, standard tray sizes, and a limited NEC 2014 Article 392.22 screening for supported cable arrangements. | infrastructure | Open tool |
| Caffeine Half-Life Calculator: When to Stop Coffee Before Bed | Caffeine half-life calculator for caffeine remaining at bedtime, latest caffeine cutoff time, and when to stop drinking coffee for sleep. Private, client-side. | fun | Open tool |
| Cake Pan Converter for Batter and Bake Time | Cake pan converter to compare round, square, rectangular, and loaf pan volumes. Scale batter amounts and estimate bake time changes. Metric and imperial support. | cooking | Open tool |
| Calories Burned Calculator by Activity | Estimate calories burned for exercise, sports, chores, work, and daily activities by duration or distance using categorized MET values. | health | Open tool |
| Camera Battery Runtime Calculator — Capacity, Power Draw & Recording Time | Estimate camera battery runtime from watt-hours or mAh, voltage, rig power draw, usable capacity, and battery count. Check target recording time and batteries needed. | studio | Open tool |
| Camera Field of View Calculator | Calculate camera angle of view, real-world frame size, focal length, distance, background coverage, and game FOV conversions from sensor size, focal length, and distance. | studio | Open tool |
| Camera Flash Guide Number Calculator — Aperture, Distance & ISO | Calculate camera-flash aperture, maximum distance, or ISO from a guide number. Supports GN in metres or feet, clear formulas, and practical flash limits. | studio | Open tool |
| Capsize Screening Formula Calculator for Sailboats | Calculate a sailboat's dimensionless capsize screening formula (CSF) from maximum beam and displacement, with metric and imperial inputs and clear safety limits. | marine | Open tool |
| Car Depreciation Calculator by Year, Mileage and Vehicle Type | Estimate current or future car value, depreciation ranges, total loss and retained value. Compare vehicle types, mileage and year-by-year resale curves. | automotive | Open tool |
| Car Insurance Calculator - Estimate Monthly and Annual Cost | Estimate monthly, six-month, and annual car insurance cost by driver, location, vehicle, coverage, deductible, mileage, and claims. Private client-side calculator. Not a quote. | finance | Open tool |
| Car Lease vs Buy Calculator | Compare car lease and purchase monthly payments, total cost, mileage charges, loan balance, resale equity, and break-even resale value over the same term. | finance | Open tool |
| Car Paint Calculator: How Much Automotive Paint Do I Need? | Estimate primer, basecoat, clearcoat, activator and reducer for a car repaint or panel repair. Compare litres, US gallons, quarts, packages and material costs. | automotive | Open tool |
| Carbon Footprint Calculator — Home Energy, Travel, Diet & Consumption | Estimate an annual personal or household carbon footprint with quick inputs, regional electricity defaults, benchmarks, flights, waste, and a ranked reduction plan. Private, client-side. | environment | Open tool |
| Carbon Offset Calculator: Trees, Renewable Energy, and Cost | Carbon offset calculator for CO2 or CO2e. Enter emissions directly or estimate from flights, driving, electricity, gas, and events, then compare trees, renewable kWh, and offset cost. | environment | Open tool |
| Carburetor Size Calculator (CFM) | Find your carb size from CID, RPM and VE: calculate engine airflow, compare common carburetor CFM sizes, and review street or high-RPM guidance. | automotive | Open tool |
| Cartesian Product Calculator | Calculate the Cartesian product of two to eight finite sets. Generate ordered tuples, check cardinality, copy results, and download CSV privately in your browser. | discrete-mathematics | Open tool |
| Cash Conversion Cycle (CCC) Calculator | Free Cash Conversion Cycle (CCC) calculator. Use financial statement amounts or enter DIO, DSO, DPO, and CCC days directly. Includes presets, interpretation, and what-if analysis. | finance | Open tool |
| Casimir Force Calculator for Parallel Plates | Calculate the ideal Casimir force and pressure between neutral parallel conducting plates in vacuum from separation, overlapping area, or plate dimensions. | science | Open tool |
| Caulk Calculator — How Many Tubes Do I Need? | Calculate how many caulk or sealant tubes you need across multiple joints. Compare cartridge and sausage-pack coverage for rectangular, triangular, and round beads. | construction | Open tool |
| CD Calculator: Estimate Certificate of Deposit Interest | Use this free CD calculator to estimate maturity value, interest earned, APY/APR growth, taxes, inflation impact, and early withdrawal penalties. | finance | Open tool |
| CDN Cache Hit Ratio Calculator: Origin Bandwidth and Egress Savings | Calculate CDN cache offload, origin bandwidth, origin egress, cost savings, target hit-ratio gains, and peak origin capacity from traffic volume or requests. | infrastructure | Open tool |
| Cell Turnover Calculator: Do Your Cells Replace Every 7 Years? | Use this cell turnover calculator to estimate how much of your skin, blood, gut, liver, bone, fat, heart and brain cells may have renewed. Learn why the “every 7 years” claim is a myth. | fun | Open tool |
| Centrifuge RPM to RCF Calculator | Convert centrifuge RPM to RCF or g-force, or calculate RPM from RCF and rotor radius. Practical lab calculator for protocols and centrifuge setup. | science | Open tool |
| Centripetal Force Calculator | Centripetal force calculator for force, mass, speed, radius, acceleration, angular velocity, period, and RPM with automatic unit conversion. | science | Open tool |
| Change of Basis Matrix Calculator | Calculate change of basis matrices between two ordered bases, transform vector coordinates, and verify C·P = B with clear steps. Supports 2×2 through 6×6 bases. | linear-algebra | Open tool |
| Chemical Equation Balancer Calculator | Balance chemical equations online using conservation of atoms. Enter reactants and products, get whole-number coefficients, atom checks, and a balanced equation. | science | Open tool |
| Child & Baby Growth Percentile Calculator — WHO and CDC | Calculate child and baby weight, length or height, BMI and head-circumference percentiles with WHO and CDC growth charts from birth through age 20. | health | Open tool |
| Chinese Remainder Theorem Calculator with Steps | Solve systems of congruences with a Chinese Remainder Theorem calculator that shows exact steps and handles compatible non-coprime moduli. | discrete-mathematics | Open tool |
| Chocolate Tempering Calculator: Seed Amount and Temperatures | Calculate chocolate seed amounts and temperatures for seeding, microwave, tabling or melter methods. Plan total or already-melted batches in grams or ounces. | cooking | Open tool |
| Cholesky Decomposition Calculator with Steps | Calculate the Cholesky decomposition A = LLᵀ for a symmetric positive-definite matrix. See L, Lᵀ, every entry formula, and a reconstruction check. | linear-algebra | Open tool |
| Cholesterol Ratio Calculator | Calculate Total/HDL, LDL/HDL, triglyceride/HDL, non-HDL cholesterol and AIP in mg/dL or mmol/L, with formulas and sourced context. | health | Open tool |
| Circle Calculator: Area, Circumference, Diameter & Radius | Enter radius, diameter, circumference, or area to instantly solve the other three circle values with units, exact π forms, and rounded decimals. | geometry | Open tool |
| Circle Chord Calculator — Chord Length, Sagitta and Central Angle | Calculate circle chord length, sagitta, radius, central angle, arc length, and segment area from any two known values. Supports minor and major segments. | geometry | Open tool |
| Circle Sector Calculator — Area, Arc Length, Radius and Angle | Calculate a circle sector's area, arc length, radius, central angle, chord, and perimeter from any two known values. Supports degrees, radians, and length units. | geometry | Open tool |
| Cloud Egress Cost Calculator: Data Transfer and Monthly Bandwidth Charges | Calculate monthly cloud egress cost with free transfer, configurable pricing tiers, processing fees, fixed charges, and average bandwidth. | infrastructure | Open tool |
| CNF and DNF Converter for Propositional Logic | Convert propositional logic formulas to equivalent canonical CNF and DNF. See minterm and maxterm indices, verify a truth table, copy results, or download them. | discrete-mathematics | Open tool |
| Coffee to Water Ratio Calculator | Coffee to water ratio calculator for drip, pour-over, French press, AeroPress, cold brew, moka pot, and espresso yield. Tune strength and get grams, ml, fl oz, scoops, grind, time, and temperature. | cooking | Open tool |
| Collisional Quantum Decoherence Time Calculator | Estimate spatial decoherence time from collisions with a dilute ideal gas using target size, mass, gas, pressure, temperature and superposition separation. | science | Open tool |
| Color Palette Generator – Random & Harmonious Color Schemes | Generate random or harmonious color palettes from a HEX color. Edit, lock, test contrast, preview, share, and export palettes in your browser. | random | Open tool |
| Color Temperature Converter — Kelvin, Mired & Gel Correction | Convert Kelvin and mired values, calculate color-temperature shift, and find approximate CTO or CTB gel correction for studio lighting. | studio | Open tool |
| Combine Like Terms Calculator — Expand and Simplify Expressions | Combine like terms, expand parentheses, and simplify multivariable expressions for free. See every distribution step, exact fractions, and numeric checks. | algebra | Open tool |
| Commission Calculator | Calculate sales commission, tiered commission, quota accelerators, splits, draws, and gross pay. Private, client-side commission calculator with CSV export. | finance | Open tool |
| Common Factor Calculator | Find all common factors of two or more integers and the greatest common factor (GCF/GCD). Shows Euclidean steps, handles negatives and large integers, and runs in your browser. | number-theory | Open tool |
| Commute Carbon Footprint Calculator: compare car, bus, train, bike and EV | Calculate your commute carbon footprint by car, bus, train, bike, carpool, hybrid, or EV. Compare daily, weekly, monthly, and annual CO₂ with regional factors and editable assumptions. | environment | Open tool |
| Compare Text Online with a Free Diff Checker | Compare text or text files online with a free, private diff checker. Review additions, deletions, and modified lines side by side in your browser. | text | Open tool |
| Comparing Fractions Calculator: Which Fraction Is Greater? | Compare fractions, mixed numbers, decimals, percentages, whole numbers, or up to five values. Get an exact greater than, less than, or equal answer with selectable steps. | algebra | Open tool |
| Completing the Square Calculator | Convert a quadratic to vertex form and, when needed, solve ax² + bx + c = 0 with exact, readable completing-the-square steps. | algebra | Open tool |
| Compost C:N Ratio Calculator: Balance Greens and Browns | Calculate compost C:N ratio, balance greens and browns, include optional moisture, and estimate how much leaves, straw, cardboard, grass, food scraps, coffee grounds, or manure to add. | agriculture | Open tool |
| Composting Carbon Footprint Calculator | Free composting carbon footprint calculator for households and programs. Estimate annual CO2e savings for food scraps and yard waste with EPA WARM v16 or custom IPCC assumptions. | environment | Open tool |
| Compound Interest and Time Value of Money Calculator | Calculate compound interest, future value, present value, deposits, schedules, APR/EAR, and time value of money formulas. Private and client-side. | finance | Open tool |
| Compound Interest Calculator — Monthly Contributions & Inflation | Free compound interest calculator with flexible contributions, APR/APY compounding presets, goal solving, growth chart, breakdown table, and inflation adjustment. Private by design. | finance | Open tool |
| Compound Interest Table Calculator | Calculate compound interest with a year-by-year table, rate comparison chart, regular contributions, APR/APY frequency presets, formulas, and CSV export. Private and fast. | finance | Open tool |
| Compound Miter Crown Molding Calculator | Calculate compound miter and bevel angles for crown molding using corner angle and spring angle. Optional molding width for cut-face length. Fast, accurate, and private. | construction | Open tool |
| Compress Images Online for Free | Compress JPG, PNG, WebP and supported modern images locally. Set quality, target KB or MB, resize, compare measured results, and download batches privately. | graphics | Open tool |
| Compress PDF Online Free | Compress PDF files in your browser with no upload, watermark, or sign-up. Reduce file size for email, uploads, 10 MB, 5 MB, or custom limits. | documents | Open tool |
| Compton Shift and Scattering Calculator | Calculate Compton wavelength shift, scattered wavelength, photon energy, and recoil electron kinetic energy from incident wavelength or photon energy plus scattering angle. | science | Open tool |
| Concrete Block Calculator | Calculate concrete blocks for multiple walls and openings, then estimate mortar, masonry grout, optional rebar, pallets, and itemized material cost. | construction | Open tool |
| Concrete Calculator: Cubic Yards, Bags, Slabs & Footings | Concrete calculator for cubic yards, cubic metres, cubic feet, bag counts, cost, waste, slabs, footings, post holes, round slabs, walls, steps, curbs and gutters. | construction | Open tool |
| Concrete Formwork and Shuttering Calculator | Calculate concrete formwork or shuttering area, plywood sheets, boards, waste, supports and cost for slabs, walls, beams, columns and footings. | construction | Open tool |
| Concrete Mix Ratio Calculator | Calculate cement, sand, aggregate, water, bags, dry volume, slab dimensions, and mixer batches for concrete mix ratios including M15, M20, and custom mixes. | construction | Open tool |
| Cone Calculator for Volume, Surface Area, Slant Height, Radius, and Height | Calculate cone volume, total and lateral surface area, slant height, radius, height, base area, circumference, and cone angles for a right circular cone. | geometry | Open tool |
| Confidence Interval Calculator — Mean, Proportion & Difference | Calculate confidence intervals for one mean, one proportion, two independent means, or two independent proportions. Includes t, z, Wilson, Welch, and Newcombe methods. | statistics-probability | Open tool |
| Conic Equation Finder Calculator | Find and classify circle, parabola, ellipse, hyperbola, and general conic equations from points, foci, directrix, parameters, or a pasted equation. Standard form, steps, graph, and derived properties. 100% client-side. | geometry | Open tool |
| Conical Frustum Calculator | Calculate a conical frustum's volume, total and lateral surface area, slant height, base areas, and diameters from two radii and height. | geometry | Open tool |
| Contents Insurance Calculator for Flats, Apartments & Renters | Calculate how much contents insurance cover you may need for a flat, apartment or rented home. Add room-by-room belongings, valuables, excess and risk factors to estimate cover and illustrative annual cost. | finance | Open tool |
| Continued Fraction Calculator and Rational Approximation Tool | Expand a fraction or decimal as a simple continued fraction, list exact convergents, and find the closest rational approximation under a denominator limit. | number-theory | Open tool |
| Conway’s Game of Life Simulator Online | Play Conway’s Game of Life simulator online. Draw cells, load classic patterns, import or export RLE, change Life-like rules, zoom the grid, and share your board. | discrete-mathematics | Open tool |
| Cooking Oil Smoke Point Chart and Temperature Finder | Search 35 cooking oils and grades, find oils for your cooking temperature, and compare smoke points, flavor, sources and adjustable planning margins in °F or °C. | cooking | Open tool |
| Coolant Mix Calculator: Antifreeze-to-Water Ratio | Calculate engine coolant ratios, premix refills, retained flush water, and drain-and-replace amounts. Compare product-specific freeze protection for a 50/50 coolant mix. | automotive | Open tool |
| Cooling Load Calculator: AC BTU / Server Room Cooling Estimator | Estimate AC BTU, tons, kW, and server room cooling load for bedrooms, offices, homes, IT rooms, and equipment spaces. Private, client-side. | infrastructure | Open tool |
| Coordinate Transformation Calculator — Translate, Rotate, Reflect & Dilate 2D Points | Transform a 2D point or shape with translation, clockwise or counterclockwise rotation, reflection, dilation (scale), or shear. See image coordinates and worked steps. | linear-algebra | Open tool |
| Coprime Number Checker & Pairwise Coprime Calculator | Check whether two integers are coprime or a list is pairwise coprime. See exact GCDs, conflicting pairs, collective GCD, and a pair table. | number-theory | Open tool |
| Corn Yield Calculator: Estimate Bushels per Acre from a 1/1000-Acre Sample | Estimate grain corn yield in bushels per acre from a 1/1000-acre sample, ear counts, kernel rows, kernels per row, and kernel-weight assumptions. | agriculture | Open tool |
| Corrected Calcium Calculator — Adjust Calcium for Albumin | Calculate albumin-corrected calcium with the common simplified Payne formula in mg/dL or mmol/L. Includes unit conversion, limitations, examples, and sources. | health | Open tool |
| Correlation Coefficient Calculator — Pearson, Spearman & Significance | Calculate Pearson r and Spearman rho for paired data, with two-sided p-values, significance, a Pearson confidence interval, ranks, and a scatterplot. | statistics-probability | Open tool |
| Coulomb's Law Calculator - Electric Force Between Charges | Use Coulomb's law to solve for electric force, charge, or distance when any three values are known. Includes unit conversions, attraction/repulsion, and step-by-step work. | science | Open tool |
| Create a Sky Map for Any Date and Place | Create a free sky map for any date and place. Plot real stars, constellations and planets, customize the design, then download a high-resolution PNG or print-ready PDF. | random | Open tool |
| Create a valid sitemap.xml — crawl or paste URLs | Crawl an accessible website or import URLs, validate and edit entries, then download specification-valid XML sitemap files without signup. | web | Open tool |
| Credit Card Payoff Calculator | Estimate how long it will take to pay off credit card debt, the monthly payment needed for a target date, payoff date, and total interest. Includes minimum payment and multi-card scenarios. | finance | Open tool |
| Credit Utilization Calculator | Calculate your overall and per-card credit utilization ratios, available credit, and the balance reduction needed to reach a target percentage. Free, private, and client-side. | finance | Open tool |
| Cron Expression Generator and Parser with Next Run Times | Generate, parse, and validate cron expressions instantly. Build Unix, Quartz, Kubernetes, AWS, and Spring cron schedules with plain-English explanations and next run previews. | time-date | Open tool |
| Crop & Combine Harvest Loss Calculator | Convert field seed counts or collected grain weight to bu/acre or kg/ha, diagnose combine loss sources, or compare yields with moisture adjustment and lost-value results. | agriculture | Open tool |
| Crop Break-Even Price & Yield Calculator — Profit per Acre | Calculate crop break-even price and yield, profit per acre, whole-field profit, cost coverage, scenarios, and price-yield sensitivity. | agriculture | Open tool |
| Crop Factor Calculator for Equivalent Focal Length and Aperture | Convert lenses between camera sensor formats. Calculate 35mm equivalent focal length, depth-of-field equivalent aperture, custom crop factors, and field of view. | studio | Open tool |
| Crop Image Online for Free | Crop an image to exact pixels or a preset ratio, then download JPG, PNG, or WebP. Private browser processing, no signup, and no watermark. | graphics | Open tool |
| Crop PDF Pages Online – Trim Margins and Resize Page Bounds | Crop PDF pages online for free. Drag page edges, enter exact margins, or detect white space, then download privately with no upload or watermark. | documents | Open tool |
| Crop Water Requirement Calculator | Crop water requirement calculator for ETc, net and gross irrigation depth, seasonal water budgets, runtime, flow, and field volume using local ETo or FAO-56 weather data. | agriculture | Open tool |
| Cross Product Calculator for 3D Vectors | Calculate A × B for two 3D vectors. See determinant steps, magnitude, unit normal, areas, angle, and perpendicularity checks; copy or download the result. | linear-algebra | Open tool |
| Crypto DCA Calculator - Backtest Bitcoin and Ethereum Recurring Buys | Backtest crypto dollar-cost averaging for Bitcoin, Ethereum, Solana, or manual prices. Compare recurring buys with lump sum, ROI, final value, fees, and cost basis. | finance | Open tool |
| Crypto HODL ROI Calculator | Calculate crypto HODL profit or loss, ROI before and after fees, CAGR, annualized return, and benchmark comparison from total values or coin buy and sell prices. | finance | Open tool |
| Crypto Loan Collateral Calculator: Required Collateral, LTV, and Liquidation Price | Calculate crypto loan collateral required, borrowing power, LTV, liquidation price, interest impact, and safer LTV adjustments. Client-side. | finance | Open tool |
| Crypto Portfolio Allocation & Rebalancing Calculator | Enter crypto holdings, set target weights, check diversification risk, and calculate buy or sell amounts for rebalancing. Private, client-side. | finance | Open tool |
| Crypto Retirement Calculator: DCA to a Retirement Goal | Estimate crypto retirement outcomes: time to goal, future value by retirement age, required DCA contribution, withdrawal duration, fees, taxes, scenarios, and yearly growth. | finance | Open tool |
| Crypto Staking Rewards Calculator | Estimate crypto staking rewards by asset, APY or APR, validator fees, compounding, gas costs, token price, and time. Private, client-side. | finance | Open tool |
| CSS Border Radius Generator & Preview | Create CSS border-radius values visually. Set each corner, build elliptical radii, try shape presets, preview the result, and copy or download clean CSS. | web | Open tool |
| CSS Box Shadow Generator & Preview | Build single or layered CSS box shadows with visual controls, presets, inset effects, a live preview, and copy-ready CSS. Free and private in your browser. | web | Open tool |
| CSS Clamp Calculator for Responsive Typography | Generate a CSS clamp() font-size from minimum and maximum type sizes and viewport widths. Preview, copy, and download fluid typography CSS privately. | web | Open tool |
| CSS Formatter, Minifier & Beautifier Online | Format, beautify, validate, or minify CSS online. Process stylesheets privately in your browser, compare exact size savings, then copy or download the result. | web | Open tool |
| CSS Gradient Generator | Create CSS gradients with draggable color stops, opacity, conic and repeating types, import/share URLs, presets, compatibility notes, and copy-ready output formats. | web | Open tool |
| CSV Viewer — Sort, Filter & Search | Open and view CSV files online in a sortable, filterable table. Search all columns, filter by column, and export filtered results. 100% client-side, no uploads. | text | Open tool |
| Cube Calculator: Volume, Surface Area, and Diagonal | Enter side length, volume, surface area, face diagonal, or space diagonal to solve all cube measurements with unit-aware outputs and steps. | geometry | Open tool |
| Cups to Grams Calculator | Convert cups, tablespoons, teaspoons, grams, ounces, milliliters, and more for common cooking ingredients. Ingredient-aware kitchen converter that runs entirely in your browser. | cooking | Open tool |
| Currency Impact on Investment Returns Calculator | Calculate how local investment performance plus exchange-rate movement changes home-currency return. Compare hedged and unhedged foreign investment results. | finance | Open tool |
| Cylinder Calculator | Solve a right circular cylinder from radius, diameter, height, area, or volume. Includes units, decimal places, and pi precision. Private and client-side. | geometry | Open tool |
| Data Center PUE Calculator | Power Usage Effectiveness Formula | Calculate data center PUE from kW or kWh, see DCiE, overhead share, IT energy share, efficiency interpretation, and target PUE savings. Private, client-side. | infrastructure | Open tool |
| Data Center White Space Capacity Planner: Racks, Power and Cooling | Estimate data center rack capacity from usable white space, facility power, PUE, sensible cooling, average rack load, reserve headroom, and a target rack count. | infrastructure | Open tool |
| Data Replication Bandwidth Calculator for RPO & WAN Sizing | Data replication bandwidth calculator for continuous, scheduled, seed, peak, multi-workload, RPO, WAN link, and outage catch-up planning. | infrastructure | Open tool |
| Database Connection Pool Size Calculator | Calculate database connection pool size per app instance from request throughput, database calls, connection hold time, utilization, burst headroom, and database connection limits. | infrastructure | Open tool |
| Date Calculator | Free Date Calculator: count days between dates, add or subtract days, weeks, months, or years, calculate business days, exclude holidays, and copy shareable results. | time-date | Open tool |
| Days Inventory Outstanding (DIO/DSI) Calculator | Calculate days inventory outstanding (DIO/DSI), days sales of inventory, days in inventory, and average age of inventory from COGS and inventory values. | logistics | Open tool |
| dBm to Watts Calculator | Convert dBm to watts, watts to dBm, dBW, Vrms, Vpp, dBV, and dBµV with 50 Ω or custom impedance. Includes clickable RF reference rows and dB ratio mode. | calculators | Open tool |
| De Broglie Wavelength Calculator | Calculate de Broglie wavelength from velocity, kinetic energy, momentum, or accelerating voltage. Includes particle presets, unit conversion, relativistic correction, worked steps, and scale comparisons. | science | Open tool |
| Deadline Calculator and Backward Planner | Calculate a latest start date or deadline using calendar days, business days, review buffers, weekends, US federal holidays, and blackout dates. | time-date | Open tool |
| Debt Avalanche Calculator: Payoff Date, Interest Saved, and Monthly Schedule | Enter multiple debts, APRs, minimum payments, and extra payoff cash to compare avalanche, snowball, and minimum-only debt payoff schedules. | finance | Open tool |
| Debt Consolidation Calculator UK | Use this debt consolidation calculator to compare your current debts with a new loan. Estimate monthly payments, total interest, fees, payoff time and savings. Private, browser-based tool. | finance | Open tool |
| Debt Snowball & Avalanche Calculator | Plan debt payoff with the Snowball or Avalanche method. See payoff date, total interest, and a month-by-month schedule. Client-side. | finance | Open tool |
| Debt-to-Income Ratio Calculator | Use this debt-to-income ratio calculator to estimate front-end and back-end DTI before applying for a mortgage, loan, or credit. Itemize housing costs, income, and monthly debts privately in your browser. | finance | Open tool |
| Decimal Degrees to DMS Converter | Convert decimal degrees to DMS for coordinate pairs, latitude, longitude, bearings, or angles. Copy five formats, check DDM, and export bulk coordinates to CSV. | calculators | Open tool |
| Deck Board Calculator: Boards, Screws, Spacing and Cost | Calculate deck boards, linear footage, screws or clips, spacing, waste and cost for straight or 45-degree layouts, with imperial and metric results. | construction | Open tool |
| Deck Joist Span Calculator | Find maximum deck joist span or check an existing span by species, joist size, and spacing using DCA6-based 40 psf live and 10 psf dead load assumptions. | construction | Open tool |
| Degree Sequence Graphicality Checker — Havel–Hakimi Algorithm | Check whether a degree sequence is graphical with the Havel–Hakimi algorithm. See every reduction step and construct a simple graph when one exists. | discrete-mathematics | Open tool |
| Density Calculator | Calculate density, mass, or volume from two known values. Supports metric, imperial, liquid, and cubic units with private client-side calculations. | science | Open tool |
| Dental Insurance Calculator: Estimate Your Annual Dental Costs | Estimate dental insurance costs by entering premiums, deductible, coinsurance, annual maximum, copays, and orthodontic benefits. Free private calculator. | finance | Open tool |
| Depreciation Calculator | Calculate annual depreciation schedules with straight-line, declining balance, double declining balance, sum-of-years-digits, and MACRS half-year table estimates. Private, client-side tool. | finance | Open tool |
| Depth of Field (DoF) Calculator | Free depth of field calculator for photographers and filmmakers. Calculate near focus limit, far focus limit, total DoF, hyperfocal distance, and circle of confusion for full-frame, APS-C, Micro Four Thirds, and custom sensors. | studio | Open tool |
| Derivative Calculator with Free Steps and Graph | Free first–fifth derivatives with steps, exact point inputs, tangent lines and interactive graphs. Separate partial and implicit differentiation modes. | calculus | Open tool |
| Determinant Calculator with Step-by-Step Expansion | Calculate determinants of 2×2 to 5×5 matrices. Choose an expansion row, see every cofactor and minor step, then copy or download the working. | linear-algebra | Open tool |
| DHCP Scope Calculator: Pool Range, Size and Lease Time | Calculate a DHCP start and end range, available addresses, utilization, lease demand, lease-time guidance, and a suitable IPv4 subnet. | infrastructure | Open tool |
| Dice Roller Online — Roll D4, D6, D8, D10, D12, D20, D100 & Custom Dice | Use this online dice roller to roll D4, D6, D8, D10, D12, D20, D100, custom dice, modifiers, and RPG notation. Client-side and private. | random | Open tool |
| Differential Equation Calculator and ODE Solver | Find exact first-order ODE solutions when supported or solve initial-value problems numerically. See genuine steps, slope fields, adaptive RK45 and method comparisons. | calculus | Open tool |
| Dilution Calculator (C1V1 = C2V2) | C1V1=C2V2 dilution calculator — solve for C1, V1, C2 or V2. Shows dilution factor, aliquot volume, and solvent to add. Supports molarity and percent units. Free, embeddable, runs entirely in your browser. | calculators | Open tool |
| Direct and Inverse Variation Calculator — Solve x, y, or k | Solve x, y, or k exactly, predict a new value, check two pairs, or identify direct and inverse variation from a table. Includes fractions, steps, and a graph. | algebra | Open tool |
| Directional Derivative Calculator | Find exact directional derivatives and gradients with rule-by-rule steps. Enter vectors, a target point, or an angle; explore a contour plot and decimal answers. | calculus | Open tool |
| Discount Calculator | Calculate final sale price, amount saved, percent off, original price, fixed amount discounts, tax, stacked discounts, and retail deal types. Privacy-first, in-browser. | finance | Open tool |
| Discriminant Calculator (b² − 4ac) With Steps | Find the discriminant from an equation or coefficients. Get exact simplified roots, step-by-step working, root verification, and a parabola graph. | algebra | Open tool |
| Disk IOPS Calculator | Calculate RAID IOPS and drive count, convert IOPS and MB/s, or estimate IOPS from latency and queue depth. Includes bottleneck caps and RAID comparison. | infrastructure | Open tool |
| Distance Between Two Points Calculator | Calculate the straight-line distance between two 2D points. Supports integers, decimals, fractions, worked steps, adjustable precision, and a coordinate graph. | geometry | Open tool |
| Distance From a Point to a Line Calculator | Find the distance from a point to a line entered as an equation, standard form, slope-intercept form, or two points. See exact steps, projection, and graph. | geometry | Open tool |
| Distance from Point to Plane Calculator (3D) | Calculate the shortest distance from a point to a 3D plane in standard, point-normal, or three-point form. See exact steps, closest point, and verification checks. | geometry | Open tool |
| Dividend Reinvestment (DRIP) Calculator | Free DRIP calculator to compare reinvested vs cash dividends. Project portfolio value, dividend income, taxes, contributions, and yield on cost. | finance | Open tool |
| Divisibility Test Calculator with Rules and Steps | Check whether one integer is divisible by another. See the exact remainder, quotient, applicable divisibility rule, and step-by-step test for common divisors. | number-theory | Open tool |
| Divisor Count and Sum of Divisors Calculator | Calculate the number and sum of positive divisors of an integer up to 1 trillion. See prime factorization, formulas, proper-divisor sum, and exact steps. | number-theory | Open tool |
| DMX Address Calculator — Fixture Channels, Start Addresses & Universes | Calculate sequential DMX start addresses from fixture channel modes and quantities. Plan universe rollover, address ranges, gaps, and export a fixture patch list. | studio | Open tool |
| DNS Propagation Time and TTL Calculator | Calculate DNS cache expiry after a change, compare live public resolver answers and TTLs, or plan when to lower TTL before a cutover. | infrastructure | Open tool |
| Dock Line Length and Diameter Calculator | Calculate transient boat dock line lengths, total rope, and a starting dock line diameter from boat length. Includes bow, stern, and spring lines in feet or meters. | marine | Open tool |
| Dog Years to Human Years Calculator | Convert dog years to human years with a breed- and size-aware calculator. Enter your dog’s age, breed, or weight to see a human-age estimate, chart, and formula. | fun | Open tool |
| Doppler Effect Calculator | Calculate Doppler effect frequency shift for sound waves. Enter source frequency, wave speed, observer speed, and source speed to find observed frequency and pitch shift. | science | Open tool |
| Dryer Cost and Line-Drying Savings Calculator | Calculate dryer cost per load, week, month, and year, then estimate energy, CO2, and clothesline or air-drying savings for electric or gas dryers. | environment | Open tool |
| Drywall Calculator: Sheets, Mud, Tape & Screws | Drywall and Sheetrock calculator for rooms, known areas, and multi-room jobs. Estimate sheets, wall and ceiling area, openings, waste, screws, tape, joint compound, corner bead, weight, and optional costs. | construction | Open tool |
| Duplicate Line Remover | Remove duplicate lines from lists and text online. Keep first or last, find repeated rows, sort results, and process .txt files privately in your browser. | text | Open tool |
| E-Waste Carbon Footprint & Recycling Impact Calculator | Calculate the CO2e avoided, weight diverted, reuse, recycling, and recoverable materials for electronics. Free, private, and client-side. | environment | Open tool |
| EBITDA Calculator | Calculate EBITDA, EBIT, EBIT margin, and EBITDA margin from revenue, expenses, net income, interest, taxes, depreciation, and amortization. Includes adjusted EBITDA add-backs. | finance | Open tool |
| Effective Interest Rate Calculator | Calculate effective annual interest rate from nominal APR and compounding frequency, or convert effective rate back to nominal APR. Includes formulas, comparison table, and balance projection. | finance | Open tool |
| Egg Size Converter: US, UK & EU Baking Conversions | Convert US/Canada, UK/EU and Australian/New Zealand egg sizes by edible weight. Use egg counts, grams, ounces or recipe scaling for whole eggs, whites and yolks. | cooking | Open tool |
| Eigenvalue and Eigenvector Calculator with Steps | Find real or complex eigenvalues and eigenvectors of 2×2 and 3×3 matrices. See the characteristic polynomial, root steps, eigenspaces, and residual checks. | linear-algebra | Open tool |
| Elastic Potential Energy Calculator | Calculate elastic potential energy, spring constant, or deformation using U = ½kx². Converts spring, length, and energy units with clear worked steps. | science | Open tool |
| Electric Car vs Gas Car Emissions Calculator | Compare EV and gas car lifecycle CO₂e by location, vehicle type, units, grid mix, fuel economy, manufacturing, and break-even mileage. | environment | Open tool |
| Electricity Grid Carbon Intensity Calculator | Calculate electricity emissions from energy use or average load, or derive grid carbon intensity from total emissions and generation. Supports g/kWh, kg/MWh, and lb/MWh. | environment | Open tool |
| Electricity Usage Calculator — Home Energy Cost & kWh | Estimate daily, monthly, and yearly kWh, electricity cost, appliance bill impact, standby load, and CO₂ for home energy usage. | environment | Open tool |
| Ellipse Calculator: Area, Perimeter, Circumference & Eccentricity | Enter semi-major axis a and semi-minor axis b to calculate ellipse area, perimeter, circumference, eccentricity, foci, vertices, and formulas with Ramanujan II recommended. | geometry | Open tool |
| Email Carbon Footprint Calculator: Estimate CO₂e from Emails and Attachments | Email Carbon Footprint Calculator: estimate CO₂e from emails and attachments using benchmark ranges or adjustable transfer, storage, recipient, and reading assumptions. Runs in your browser. | fun | Open tool |
| Emergency Fund Calculator: How Much Should I Save? | Calculate how much to save in an emergency fund from essential expenses, income, savings, and contributions. See your target range, shortfall, and time to goal. | finance | Open tool |
| Emoji Catcher — Gentle Typing Practice | A calm typing game with falling emojis. Type the word on each emoji to catch it, one at a time, with a slow pace, lives, and word-length scoring. | games | Open tool |
| Empirical Formula Calculator | Find empirical formulas and molecular formulas from element masses or percent composition. Converts grams to moles, normalizes ratios, and checks molecular mass. | science | Open tool |
| Engine Compression Ratio Calculator | Calculate static engine compression ratio from bore, stroke, chamber, gasket, piston, and deck-clearance measurements in metric or imperial units. | automotive | Open tool |
| Engine Displacement, CC & CID Calculator | Calculate engine size in cc, liters and CID from bore, stroke and cylinders in mm or inches. Solve for bore or stroke and compare overbore or stroker builds. | automotive | Open tool |
| Engine Piston Speed Calculator | Calculate mean engine piston speed from stroke and RPM. Convert instantly between m/s, ft/min, km/h, and mph, with stroke frequency and clear formulas. | automotive | Open tool |
| Enzyme Kinetics Calculator — Michaelis–Menten Plots & Curve Fitting | Free enzyme kinetics calculator: plot Michaelis–Menten curves and fit Vmax and Km from your experimental data using nonlinear regression. Includes Lineweaver–Burk, Eadie–Hofstee, Hanes–Woolf, inhibition models, Hill kinetics, bootstrap 95% CI, and SVG/PNG export. Runs entirely in your browser. | science | Open tool |
| EOQ Calculator (Economic Order Quantity) | Calculate economic order quantity (EOQ), order frequency, and annual ordering vs holding costs. Privacy-first, browser-based inventory planning. | logistics | Open tool |
| Equation of a Circle Calculator From Center, Radius or Three Points | Find a circle equation from center and radius, center and a point, or three points. Get standard and general forms, steps, graph, radius, area, and circumference. | geometry | Open tool |
| Equilibrium Constant Calculator for Kc, Kp and Q | Calculate equilibrium constants Kc and Kp from a balanced reaction, compare Q with K to predict direction, and convert Kc ↔ Kp using temperature and Δn(gas). Private and client-side. | science | Open tool |
| Equivalence Relation and Equivalence Class Calculator | Test a finite relation for reflexivity, symmetry, and transitivity, then find every equivalence class and a chosen element’s class with counterexamples. | discrete-mathematics | Open tool |
| Escape Velocity Calculator | Calculate escape velocity from mass and radius, presets for planets and major moons, altitude, and output units including km/s, m/s, mph, km/h, and ft/s. | science | Open tool |
| Ethernet Cable Distance and Speed Checker | Check Cat5e, Cat6 or Cat6A Ethernet channel distance against 100M, 1G, 2.5G, 5G and 10GBASE-T reach guidance. Includes patch cords and clear caveats. | infrastructure | Open tool |
| Euler Path and Circuit Finder for Graphs | Find an Euler path or circuit in an undirected or directed graph. Check connectivity and vertex degrees, then copy or download the complete trail. | discrete-mathematics | Open tool |
| Euler’s Totient Function Calculator with Steps | Calculate Euler's totient φ(n) from 1 to 1 trillion. See prime factorization, the product formula, exact substitution steps, and small coprime lists. | number-theory | Open tool |
| EV Charging Time Calculator — How Long Will It Take? | Calculate EV charging time for household outlets, Level 2 AC and DC fast chargers. Compare speeds, overnight charge, required power, energy, optional range and cost. | automotive | Open tool |
| EV Range Calculator for Real-World Driving | Estimate full-charge and remaining EV range from rated range or battery capacity. Compare temperature, highway speed, reserve and driving conditions. | automotive | Open tool |
| Excavation Swell Calculator: Bank to Loose Volume and Truck Loads | Estimate bank volume, loose volume, truck loads, optional tonnage, and compacted backfill volume. Includes editable swell factors for common excavation materials. | construction | Open tool |
| Exhaust Pipe Size Calculator by Horsepower — Single or Dual | Enter horsepower for single or true-dual exhaust sizing in inches and mm, or look up a pipe’s horsepower band. Includes OD/ID measurements and source charts. | automotive | Open tool |
| Expected Value Calculator — Discrete Outcomes, Variance & Standard Deviation | Calculate expected value, variance, standard deviation, and E(X²) for a discrete probability distribution, with weighted contributions and clear steps. | statistics-probability | Open tool |
| Exponent Calculator with Steps | Calculate x^n with steps for positive, negative, decimal, and fractional exponents. Solve for the result, exponent, or base with exact answers and decimal approximations. | algebra | Open tool |
| Exposure Value Calculator | Calculate EV and EV100 from aperture, shutter speed, and ISO, or solve for a missing camera setting. Includes equivalent exposures and clear formulas. | studio | Open tool |
| Extended Euclidean Algorithm Calculator with Bézout Coefficients | Find the GCD and Bézout coefficients x and y with the extended Euclidean algorithm. See exact division steps, verify ax + by = gcd(a,b), and copy results. | number-theory | Open tool |
| Extract Figures from PDF Online | Extract embedded PDF images or crop complete figures, charts, tables and diagrams online for free. Export PNG, JPG or WebP locally without uploading your PDF. | science | Open tool |
| Fabric Yardage Calculator for Sewing, Curtains, Cushions and Rectangular Pieces | Estimate fabric yardage for curtains, cushions, upholstery, table linens, quilts, simple garment pieces, and rectangular sewing projects with repeats, shrinkage, and store rounding. | calculators | Open tool |
| Fan Noise Calculator: Sound Power Level from CFM, Static Pressure, and Motor Power | Fan noise calculator and sound power level calculator for estimating Lw/LN from motor power, static pressure, airflow, fan type, octave bands, and listener distance. | science | Open tool |
| Farm Pond Volume Calculator — Gallons, Acre-Feet and Irrigation Capacity | Calculate farm pond gallons, acre-feet, usable storage and irrigable acreage from area, dimensions, pond shape and depth, with optional seasonal irrigation planning. | agriculture | Open tool |
| FASTA, DNA & Protein Sequence Cleaner and Validator | Clean and validate FASTA, DNA, RNA, or protein sequences. Strip headers, line numbers, spaces, hidden formatting, and verify strict DNA, IUPAC DNA/RNA, or protein residues. | science | Open tool |
| Faucet Aerator Water Savings Calculator | Compare faucet and aerator flow rates to estimate annual water savings, variable utility savings, project cost, and simple payback in gallons or litres. | environment | Open tool |
| Fence Material Calculator | Create a fence material shopping list and cost estimate for privacy, picket, board-on-board, shadowbox, horizontal, panel, and post-and-rail fences. | construction | Open tool |
| Fermentation Salt Calculator | Calculate salt for vegetable fermentation by water weight or total batch weight. Check an existing brine percentage with clear formulas and unit conversions. | cooking | Open tool |
| Fertilizer Application Rate Calculator: lb/acre, kg/ha, per 1,000 sq ft, bags needed | Calculate fertilizer application rates, nutrient supplied, bag counts, costs, and comparisons per acre, hectare, 1,000 square feet, or metric garden units. | agriculture | Open tool |
| Fiber Optic Loss Budget Calculator | Calculate a fiber optic link loss budget, optical power budget, receiver margin, overload risk, and maximum supported reach. Private, client-side. | infrastructure | Open tool |
| Field Drainage Tile Spacing Calculator | Calculate theoretical field tile drain spacing with iterative Hooghoudt and NRCS ellipse methods, compare scenarios, or evaluate an existing layout. | agriculture | Open tool |
| File Size to Printed Pages Calculator | Estimate how many printed pages, duplex sheets, reams, weight, stack height, and cost a text file, word count, character count, or pasted text would take. | fun | Open tool |
| Fill and Annotate PDF Online – Add Text, Checkmarks and Notes | Fill and annotate a PDF online for free. Add text, checkmarks, checked boxes, and notes, then download privately with no file upload or watermark. | documents | Open tool |
| Fill Rate Calculator: Unit, Order, Line & Backorder Fill Rate | Calculate unit, order, line, case, warehouse, or vendor fill rate with shipped or backorder inputs, target gaps, and multi-line totals. Private, browser-based. | logistics | Open tool |
| Filter Step-Up Ring Finder — Lens and Filter Thread Sizes | Find the exact step-up or step-down ring for a camera lens and screw-in filter. Enter both thread diameters to get the correct adapter marking and fit notes. | studio | Open tool |
| Find and Replace Text Online | Find and replace text online: paste text, enter find and replace values, choose options, then copy or download the result. Private browser-based processing. | text | Open tool |
| FIRE Calculator: When Can I Retire Early? | Answer “When can I retire early?” with a FIRE calculator that estimates your FI number, years to FI, FI age, savings rate, taxes, fees, scenarios, and sensitivity. | finance | Open tool |
| Firewall Rule Capacity Calculator: Forecast Rulebase Growth and Cleanup | Estimate when firewall rules, deployed entries, vendor units, or objects reach a planning ceiling. Compare growth ranges, migration spikes, and cleanup targets. | infrastructure | Open tool |
| Fiscal Quarter Calculator – Find Q1–Q4 Dates | Find the calendar or fiscal quarter, fiscal year, start date, end date, and progress for any date. | time-date | Open tool |
| Flash Duration Motion Freeze Calculator | Calculate motion blur distance from flash duration, subject speed, and movement angle—or find the speed limit or t0.1 duration needed for a blur target. | studio | Open tool |
| Flight Carbon Footprint Calculator | Estimate flight CO₂ and CO₂e by airport route, stopover, distance, passengers, seat class, aircraft type, and RFI. Private, 100% client-side. | environment | Open tool |
| Flip a Coin Online — Heads or Tails Coin Flipper | Flip a coin online for a free, instant heads-or-tails result. Run 1, 3, 10, 100, or 1,000 virtual coin tosses, use custom choices, and view complete statistics. | random | Open tool |
| Floor Vibration Calculator: Natural Frequency & Walking Resonance Check | Floor vibration calculator for bouncy floors, footfall resonance, gym/dance floors, and machine RPM checks. Estimate natural frequency, harmonics, risk level, and next actions. | science | Open tool |
| Floppy Disk Calculator: How Many Floppies for GB, TB, or Cloud Storage? | Calculate how many standard 1.44 MB floppy disks you need for MB, GB, TB, cloud storage, phone libraries, backups, and game installs, with CD, DVD, Blu-ray, Zip, Jaz, and VHS comparisons. | fun | Open tool |
| FOB vs CFR Landed Cost Calculator | Compare FOB and CFR supplier quotes side by side. Calculate total and per-unit import landed cost with freight, insurance, customs value, duty, VAT/GST, destination fees, FX, and margin. | finance | Open tool |
| Food Carbon Footprint Calculator by Meal and Ingredient | Estimate a meal's carbon footprint ingredient by ingredient. Add food weights, use editable global-average factors, compare contributions, and export results. | environment | Open tool |
| Food Waste Methane Emissions Calculator — Landfill CH4 and CO2e | Estimate methane generated, emitted after landfill controls, and avoided through food-waste diversion with EPA-aligned and IPCC-style methods. | environment | Open tool |
| FPS to Hz, Frame Time, and Refresh Rate Match Calculator | Convert frames per second to Hertz, see frame time in milliseconds, and check how it lines up with your monitor refresh rate. Runs entirely in your browser. | studio | Open tool |
| Fractal Generator Online - Mandelbrot, Julia Set & Zoom Explorer | Explore Mandelbrot, Julia, Burning Ship, and Tricorn fractals online. Zoom, pan, change palettes and iterations, copy share links, and download PNG images. Runs privately in your browser. | science | Open tool |
| Fraction Calculator | Add, subtract, multiply and divide fractions with exact answers and worked steps. Convert mixed numbers, repeating decimals and percentages, compare fractions and find LCDs. | algebra | Open tool |
| Fraction Pizza — Visual Fractions | Free interactive fraction visualizer for kids and classrooms. Click pizza slices to fill them and instantly see the fraction, decimal, and percent. Includes equivalent fractions, compare mode, challenge packs, printable worksheets, and colorblind-safe themes. No login, works in browser. | games | Open tool |
| Frame Rate Conversion Calculator — Speed Change, Conform & Pulldown | Calculate frame-rate conform speed, clip duration, audio pitch shift, duration-preserving frame counts, cadence ratios, and 2:3 pulldown matches. | studio | Open tool |
| Free 1 Minute Typing Test | Take a free 1 minute typing test with WPM, accuracy, errors, CPM, KPS, missed keys, progress tracking, and a printable typing certificate. | games | Open tool |
| Free Barcode Generator Online | Create printable Code 128, EAN-13, UPC-A, EAN-8, Code 39 and ITF-14 barcodes in your browser. Download SVG/PNG, batch-generate from CSV, or print label sheets. | graphics | Open tool |
| Free Base64 Encoder & Decoder Online | Free Base64 encoder/decoder. Convert text or files to Base64 and back with URL-safe output, padding toggle, validation, and counters. 100% client-side. | web | Open tool |
| Free Bulk Image Resizer & Converter | Resize multiple images at once in your browser. Convert JPG, PNG or WebP, keep aspect ratio, and download individual files or a ZIP. Free, no signup. | graphics | Open tool |
| Free Case Converter — Uppercase, Lowercase, Title Case and More | Free online case converter for uppercase, lowercase, sentence case, title case, camelCase, snake_case and more. Private, instant and entirely browser-based. | text | Open tool |
| Free Crop Rotation Planner for Vegetable Garden Beds | Create a free 3- or 4-year crop rotation from garden-bed history, check plant-family conflicts, and generate local planting dates. No signup required. | agriculture | Open tool |
| Free Crypto Profit Calculator | Free crypto profit calculator for Bitcoin, Ethereum, and other coins. Calculate profit/loss, ROI, fees, breakeven price, and optional after-tax gains from investment amount or quantity. | finance | Open tool |
| Free Fall Calculator | Free fall calculator with units: solve for fall time, distance, impact speed, initial velocity, or gravity with steps, graph, and no-air-resistance assumptions. | science | Open tool |
| Free Favicon Generator | Free favicon generator for favicon.ico, PNG, SVG, Apple Touch Icon, Android icons, site.webmanifest, and ready HTML tags — runs in your browser with no upload. | web | Open tool |
| Free Keyword Density Checker for URL or Text | Free keyword density checker for URLs, pasted text, and text files. Analyze words, 2-grams, 3-grams, 4-grams, placement signals, stop words, and exclusions. | text | Open tool |
| Free Markdown to PDF Converter — Private Online Tool | Use this free online converter to open a Markdown file, edit with a live preview, and save a polished PDF with no signup. Your document stays in your browser. | documents | Open tool |
| Free Mental Math Trainer: Arithmetic Speed Practice | Practice addition, subtraction, times tables, division, fractions, percentages, doubles, halves, number bonds, decimals, and squares in timed or relaxed mental math rounds. | games | Open tool |
| Free Meta Tag Generator for SEO, Open Graph and Twitter/X Cards | Generate clean SEO meta tags, Open Graph, and Twitter cards. Copy or download a ready-to-paste <head> block. 100% client-side and private. | web | Open tool |
| Free Nutrition Label Generator | Create and download a printable FDA-style Nutrition Facts label for recipes, cottage-food products, packaged foods, beverages, and meal planning. | cooking | Open tool |
| Free Online Kaleidoscope Generator & Drawing Tool | Make, draw, or turn a photo into a kaleidoscope online. Control 2–32 sectors, true mirror symmetry, colors, brushes, seeds, and download a PNG. Free and private. | random | Open tool |
| Free Online Meme Generator | Make memes online for free with templates or your own JPG, PNG, or WebP. Add captions, images, and stickers, then download without signup or a watermark. | graphics | Open tool |
| Free Online Memory Match Game: matching pairs, memory game, and concentration game | Play a free online memory match game with matching pairs, concentration rules, board sizes from beginner to expert, timed and two-player modes, themes, badges, and local-only scores. | games | Open tool |
| Free Online Planetarium – Interactive Night Sky Map | Explore a free online planetarium showing the stars, planets, Moon and constellations visible from your location at any date and time. | science | Open tool |
| Free Online Pomodoro Timer | Use a free online Pomodoro timer with a ready-to-start 25/5 focus cycle, task tracking, schedule presets, alarms, local stats, and CSV export. | time-date | Open tool |
| Free Online Western Blot Image Cleaner | Free online western blot image cleaner. Upload a western blot or gel image to invert colors, adjust contrast, reduce background haze, and export a clean PNG locally in your browser. | science | Open tool |
| Free Online Word Counter — Count Words, Characters, Sentences & Paragraphs | Free online word counter with live word, character, sentence, paragraph, goal, reading-time, and writing analysis tools. No signup; text stays in your browser. | text | Open tool |
| Free Online YAML to JSON Converter | Validate YAML and convert single documents or multi-document streams to formatted or minified JSON. Open .yaml and .yml files privately in your browser. | web | Open tool |
| Free Placeholder Image Generator – Custom Size, Color & Text | Create free custom placeholder and dummy images with any size, color, text and style. Preview instantly and download SVG, PNG, JPG or WebP in your browser. | graphics | Open tool |
| Free Printable Calendar Generator | Free printable calendar generator for monthly, weekly, yearly, quarterly, academic-year and custom calendars. Add holidays and events, then download a private PDF. | time-date | Open tool |
| Free Printable Flashcard Generator | Make printable flashcards from CSV or pasted text. Generate A4 or Letter PDFs with cut marks, borders, and double-sided fronts/backs. Free, private, no signup, no uploads. | graphics | Open tool |
| Free Printable Maze Generator | Create free printable mazes for kids, classrooms, and puzzle books. Choose size and difficulty, show the solution, then download as PDF, PNG, or SVG. | random | Open tool |
| Free Printable Sudoku Generator with Answer Keys | Create free printable 9x9 Sudoku puzzles by difficulty. Generate easy, medium, hard, or expert puzzles, download PDFs, print worksheets, and include answer keys. | random | Open tool |
| Free QR Code Generator — No Sign-Up, No Expiry, No Watermark | Create free static QR codes for URLs, Wi-Fi, contacts, email, SMS, phone, locations and events. Private browser processing, PNG and SVG downloads, no sign-up, expiry or watermark. | graphics | Open tool |
| Free Readability Checker and Reading Level Calculator | Check English text readability and reading level free. Get a clear verdict, Flesch score, grade, reading age, Dale–Chall, SMOG, sentence guidance, and audience comparison. | text | Open tool |
| Free Recipe Cost Calculator — Cost Per Serving & Menu Price | Use package prices and recipe quantities to calculate ingredient cost, batch cost, cost per serving, food-cost percentage, and an optional menu price. | cooking | Open tool |
| Free Research Abstract Formatter | Clean text pasted from PDFs or LaTeX, format IMRaD and custom structured abstracts, check sections and word limits, then copy clean text locally in your browser. | science | Open tool |
| Free Robots.txt Generator & Tester | Create, validate, test, copy, and download a robots.txt file for free. Import existing files, test crawler access, and catch risky rules in your browser. | web | Open tool |
| Free Server Rack Elevation Planner & Diagram Tool | Build, validate, save, and export printable front and rear 19-inch server rack elevations. Drag equipment into U positions locally with no signup. | infrastructure | Open tool |
| Free Time Card Calculator: Hours, Breaks, Overtime & Pay | Free weekly and biweekly time card calculator for multiple shifts, lunch breaks, overtime, double time, hourly pay, CSV export, and printing. | time-date | Open tool |
| Free Travel Packing List Generator | Create a free personalized, editable and printable travel packing checklist using destination, dates, weather, trip length, luggage, laundry, travelers and activities. No signup. | logistics | Open tool |
| Free URL Slug Generator | Free URL slug generator for titles, products, and pages. Create lowercase, URL-safe slugs, preview the full URL, compare variants, or convert lists in bulk. | web | Open tool |
| Free Wallpaper Resizer & Cropper — Fit Photos to Any Screen | Resize and crop an existing photo for phone, desktop, laptop, tablet, TV, or ultrawide screens. Preview every crop, protect safe areas, and download privately. | graphics | Open tool |
| Free Word Search Maker & Generator | Free word search maker for custom printable puzzles. Add your words, choose difficulty and directions, then download a puzzle and answer key PDF. No sign-up; private in your browser. | games | Open tool |
| Freight Carbon Emissions Calculator by Shipping Mode | Calculate and compare freight CO₂e per shipment for truck, rail, air, and sea, including multimodal legs, sourced factors, savings, CSV, and print output. | logistics | Open tool |
| Freight Cost Calculator: Estimate LTL and Truckload Shipping Cost | Estimate LTL, truckload, partial, intermodal, air, or ocean freight shipping cost with route, shipment dimensions, density, fuel, accessorials, and quote assumptions. | logistics | Open tool |
| Fuel Cost Calculator | Fuel cost calculator for trips, commutes, and route planning. Calculate gas cost from distance, MPG or L/100km, fuel price, passengers, and round trips. | logistics | Open tool |
| Fuel Injector Size Calculator | Calculate fuel injector size, supported horsepower, or injector duty cycle from engine power, BSFC, injector count, and fuel density. Converts lb/hr and cc/min. | automotive | Open tool |
| Function Composition Calculator — Evaluate f(g(x)) | Evaluate f(g(x)) from two function rules and an x-value. See the composed expression, substitution steps, inner value, final result, and order comparison. | algebra | Open tool |
| Future Value Calculator | Free future value calculator for present value, recurring deposits, compounding frequency, contribution timing, inflation, fees, copyable results, and CSV schedules. | finance | Open tool |
| Gas Mileage Calculator | Calculate actual gas mileage from distance and fuel used. Convert US MPG, imperial MPG, L/100 km and km/L, plus fuel cost per mile or kilometer. | automotive | Open tool |
| GDP Calculator (Gross Domestic Product) | Free GDP calculator for nominal GDP, real GDP, and GDP deflator. Calculate GDP from consumption, investment, government spending, exports, imports, or income components. | finance | Open tool |
| Gear Ratio and RPM Calculator | Calculate engine RPM, road speed, transmission gear ratio, or final-drive ratio from tire size and gearing. Includes mph, km/h, RPM tables, formulas, and clear assumptions. | automotive | Open tool |
| Generator Fuel Consumption Calculator: Runtime and Cost | Calculate generator fuel use per hour, runtime from available fuel, and fuel cost for diesel, gasoline, propane, and natural gas. Includes lookup estimates, manual burn-rate input, charts, and examples. | infrastructure | Open tool |
| Generator Size Calculator: kW, kVA, Running Watts, and Starting Watts | Generator wattage and sizing calculator with appliance worksheet, running watts, starting watts, kW, kVA, amps, derating, and standard generator size recommendations. | infrastructure | Open tool |
| Geometric Transformation Matrix Calculator — Translate, Rotate, Scale and Reflect | Compose 2D translation, rotation, scale, and reflection matrices in order. Transform points, inspect the combined 3×3 matrix, and copy or download results. | linear-algebra | Open tool |
| Gibbs Free Energy Calculator | Calculate Gibbs free energy from enthalpy, entropy, and temperature, or connect standard free energy to equilibrium constant using Delta G standard = -RT ln K. | science | Open tool |
| Golden Ratio Calculator | Find the shorter part, longer part, total length, and golden rectangle dimensions. Includes worked steps, examples, and a ratio checker. Private and client-side. | geometry | Open tool |
| GPA Calculator — Weighted & Unweighted (4.0 / 4.33) + Cumulative | Free GPA Calculator: weighted & unweighted on 4.0 or 4.33 scales, with cumulative GPA and grade-needed estimator. Fast, private, 100% client-side. | calculators | Open tool |
| Grain Bin Calculator: Bushels, Capacity and Weight | Calculate current, maximum and remaining grain-bin bushels, fill height and weight for round bins, rectangular storage, peaks, withdrawal cones and hoppers. | agriculture | Open tool |
| Grain Moisture Calculator: Wet-to-Dry Bushels, Shrink & Drying Cost | Convert wet grain to dry bushels, compare shrink methods, estimate drying costs and elevator deductions, and compare selling wet versus drying. | agriculture | Open tool |
| Gram–Schmidt Orthonormalization Calculator | Orthonormalize vectors with the modified Gram–Schmidt process. See Q, R, orthogonal vectors, projection steps, and numerical accuracy checks. | linear-algebra | Open tool |
| Graph Coloring Calculator — Find Chromatic Number and Coloring | Find the chromatic number of a simple undirected graph and get a valid minimum vertex coloring. Visualize color classes, copy results, and download CSV. | discrete-mathematics | Open tool |
| Graph Theory Calculator | Enter an undirected or directed graph to calculate vertices, edges, degrees, density, connectivity, components, cycles, tree, bipartite, complete, regular, and Euler properties. | discrete-mathematics | Open tool |
| Gravel Calculator: How Much Gravel Do I Need? | Estimate gravel quantity, tons, cubic yards, coverage, overage, and cost. Supports rectangles, total area, volume, circles, triangles, unit switching, and material density presets. | construction | Open tool |
| Gravity Calculator: Surface Gravity, Weight on Planets, and F = ma | Calculate surface gravity, weight on planets and moons, Newton's second law, and two-body gravitational force with units, steps, examples, and comparison cards. | science | Open tool |
| Green Screen Size Calculator | Calculate green screen width and height from camera distance, subject separation, focal length, sensor size, aspect ratio, framing margin, and screen overscan. | studio | Open tool |
| Greenhouse Heater Size & Heating Cost Calculator (BTU/kW) | Estimate greenhouse heater size in BTU/h and kW, monthly or seasonal energy use, fuel costs, and savings from insulation upgrades using local climate data. | agriculture | Open tool |
| Greenhouse Roof Angle Calculator for Winter Sun and Latitude | Find greenhouse roof pitch from location, latitude, winter sun angle, orientation, and practical design constraints for fixed or adjustable glazing. | agriculture | Open tool |
| Greywater / Graywater Calculator: Estimate Reuse, Tank Size, Toilet & Irrigation Savings | Greywater and graywater calculator for estimating reuse volume, tank size, toilet flushing and irrigation savings, tariffs, sewer credits, and simple payback. | environment | Open tool |
| Grow Light Electricity Cost and DLI Calculator | Calculate grow light electricity cost, PPFD to DLI, target DLI schedules, fixture coverage, and setup comparisons for indoor gardening and controlled-environment agriculture. | agriculture | Open tool |
| Growing Degree Days (GDD/GDU) Calculator | Calculate daily or cumulative growing degree days for crops, pests, corn 86/50 GDU, base temperature models, and season target planning. | agriculture | Open tool |
| Gutter Size Calculator — Downspout Size and Count | Size K-style or half-round gutters and calculate downspout size, count, spacing, outlet area, roof runoff, and section load in imperial or metric units. | construction | Open tool |
| Half-Life Calculator for Radioactive Decay | Calculate remaining amount, initial amount, elapsed time, half-life, decay constant, and mean lifetime for exponential radioactive decay. Client-side and unit-aware. | science | Open tool |
| Harvest Date & Sowing Planner | Plan planting schedules by calculating harvest windows from sowing date and days to maturity. Includes frost risk checks for gardeners and farmers. | agriculture | Open tool |
| Hasse Diagram Generator for Partially Ordered Sets | Generate a Hasse diagram from a finite partial order or cover relations. Validate the poset, find cover pairs, minimal and maximal elements, then copy or download results. | discrete-mathematics | Open tool |
| Hay Bale Weight Calculator: Bales Needed for Livestock | Estimate round or square hay bale weight, dry matter, days per bale, bales needed, daily hay demand, inventory life, and feed cost for livestock. | agriculture | Open tool |
| HbA1c Converter: A1C to eAG, IFCC, NGSP and Blood Sugar | Convert HbA1c (NGSP % ↔ IFCC mmol/mol) and estimated average glucose (eAG) in mg/dL ↔ mmol/L. Fast, calm UI. Private—runs in your browser. | health | Open tool |
| Health Insurance Cost Calculator: Compare Premiums, Deductibles, Copays, and Out-of-Pocket Maximums US-first | Compare health insurance plans by annual premiums, deductible, copays, coinsurance, expected yearly cost, and worst-case yearly cost. US-first, private, browser-based estimator. | finance | Open tool |
| Heart Beats Counter: Measure BPM and Estimate Lifetime Beats | Tap each pulse to measure BPM, estimate beats per day, year, and lifetime, compare common scenarios, and check normal heart-rate ranges. | health | Open tool |
| Heart Rate Zone Calculator | Calculate target exercise heart-rate zones in BPM using age, measured maximum heart rate, or heart-rate reserve. Free, private, client-side tool. | health | Open tool |
| Heat Pump vs Gas Furnace Cost Calculator | Compare heat pump, electric resistance, and gas furnace or boiler running costs, savings, break-even COP, and CO₂ with editable rates and presets. | environment | Open tool |
| Heat Pump Water Heater Savings & Payback Calculator | Calculate heat pump water heater cost, annual savings, payback, ROI, and lifetime cash flow versus electric or gas. Includes bill-based inputs and local rates. | environment | Open tool |
| Heisenberg Uncertainty Principle Calculator | Heisenberg uncertainty principle calculator for position, momentum, velocity, energy, and time. Supports SI, eV, eV/c, nm, Å, fs, and more. | science | Open tool |
| HELOC Calculator | Estimate HELOC borrowing capacity, CLTV, interest-only draw payments, repayment-period payments, and total interest. Private, client-side home equity line of credit calculator. | finance | Open tool |
| Herbicide Rate Calculator and Pesticide Mix Calculator | Herbicide and pesticide mix calculator for product per gallon, per tank, per acre, per 1,000 sq ft, partial tanks, banded applications, and calibrated sprayers. | agriculture | Open tool |
| Heron’s Formula Calculator | Enter the three side lengths a, b, c to compute triangle area using Heron’s formula. Shows semiperimeter, perimeter, inradius, circumradius, and heights. Private, 100% client-side. | geometry | Open tool |
| Hessian Matrix and Critical Point Calculator | Calculate a symbolic Hessian matrix, find critical points numerically, and classify local minima, maxima, saddle points, or degenerate cases with steps. | calculus | Open tool |
| High Altitude Baking Calculator and Adjustment Chart | High altitude baking calculator and chart for baking powder, baking soda, liquids, sugar, flour, oven temperature, bake time, eggs, yeast, and fat by elevation. | cooking | Open tool |
| Highly Composite Number and Divisor Record Finder | Find every highly composite number up to 1 quintillion. See divisor-count records, prime factorizations, exact tau values, and downloadable results. | number-theory | Open tool |
| Hohmann Transfer Calculator — Orbit Transfer Δv & Time of Flight | Calculate Hohmann transfer burns, total delta-v, transfer time, transfer ellipse details, optional plane change, and propellant mass for the Sun, Earth, Moon, Mars, Venus, Jupiter, and custom bodies. | science | Open tool |
| Holiday Countdown — Christmas, Halloween & More | Live Holiday Countdown: see days, hours, minutes, and seconds until Christmas, Halloween, New Year’s and more. Includes a custom date countdown. 100% client-side for privacy. | time-date | Open tool |
| Home Air Sealing Carbon Savings Calculator | Estimate annual and long-term operational CO2 savings from home air sealing using your heating and cooling energy, audit reduction, and editable emissions factors. | environment | Open tool |
| Home Energy Vampire Power Cost Calculator | Calculate standby vampire power in watts, kWh, annual electricity cost, avoidable savings, and CO2 for TVs, consoles, chargers, and other home devices. | environment | Open tool |
| Home Insurance Calculator: Estimate Buildings, Contents and Annual Cost | Estimate home insurance cost, buildings cover and contents cover with regional defaults, transparent methodology and practical cost drivers. Educational only, not a quote. | finance | Open tool |
| Home Water Leak Waste & Cost Calculator | Estimate water wasted and utility cost from a dripping faucet, leaking toilet, pipe, or measured household leak. Free, private, client-side calculator. | environment | Open tool |
| Horsepower to Torque Calculator | Convert horsepower, torque, and RPM. Calculate lb-ft, N·m, mechanical hp, metric hp, kW, or shaft speed instantly with formulas and unit conversions. | automotive | Open tool |
| Hourly to Annual Salary Calculator | Convert hourly wage to annual salary instantly with pay-period breakdowns, overtime, PTO and holiday adjustments, and an optional simplified after-tax estimate. | finance | Open tool |
| Household Appliance Carbon Emissions Calculator | Estimate annual electricity use and CO2 emissions for refrigerators, washers, TVs, computers, kitchen appliances, and other household devices. | environment | Open tool |
| Household Waste Audit Calculator and Diversion Planner | Audit household rubbish, recycling, compost and reuse by weight. Calculate diversion, annual waste, per-person generation, target gaps and a practical category plan. | environment | Open tool |
| How Long Does Plastic Take to Decompose in the Ocean? Timeline & Calculator | See sourced estimates for how long plastic bags, bottles, fishing line and other debris persist in the ocean, with a searchable lookup and comparison chart. | environment | Open tool |
| How Long Is a Roll of Toilet Paper? Length Calculator | Calculate toilet paper roll length from package details or estimate a partly used roll from its diameter. See metres, feet, sheets, area, formulas, and examples. | fun | Open tool |
| How Long to Boil Eggs Calculator for Soft, Jammy, and Hard-Boiled Eggs | How long to boil eggs for soft, jammy, medium, or hard-boiled results. Egg boil calculator with live timer, altitude presets, method choice, and ice bath timing. | cooking | Open tool |
| How Loud Is Too Loud? Decibel Safety Calculator | Check whether a dBA level and exposure time are likely OK, need caution, or are too loud for that long. Includes NIOSH, OSHA, everyday listening, dose rows, and ear protection estimates. | fun | Open tool |
| How Many Browser Tabs Is Too Many? | Find out whether your open browser tabs are comfortable, crowded, or overloaded. Compare your current tab count with a practical cleanup plan. 100% client-side. | fun | Open tool |
| How Many Earths Fit in the Sun? Calculator and Formula | About 1.3 million Earths fit inside the Sun by volume. See the formula, NASA-sourced values, packed-sphere estimate, comparison table, and calculator. | fun | Open tool |
| How Many Wi-Fi Access Points Do I Need? AP Calculator | Estimate how many Wi-Fi access points you need from area, floors, building conditions, connected devices, applications, and Wi-Fi generation. | infrastructure | Open tool |
| How much can insulation and air sealing save? | Estimate insulation, air-sealing, duct-sealing, and draft-control savings. Compare projects, payback, ROI, lifetime value, NPV, and conservative-to-optimistic ranges. | environment | Open tool |
| How Much House Can I Afford? | Estimate how much house you can afford from income, debts, down payment, mortgage rate, taxes, insurance, HOA, PMI, closing costs, and reserves. 100% client-side. | finance | Open tool |
| How Much Siding Do I Need? Siding Calculator: Squares, Panels, Trim and Cost | How much siding do you need? Calculate wall and gable area, openings, squares, cartons, panels, trim accessories, house wrap, fasteners, waste, and cost. | construction | Open tool |
| HTML Color Picker | Pick a color visually or from an image, convert HEX, RGB, HSL, HSV and OKLCH, build palettes, and check WCAG 2.2 contrast locally in your browser. | web | Open tool |
| HTML Formatter, Minifier & Beautifier Online | Format, beautify, validate, preview, or minify HTML online in your browser. Paste code or open a local HTML file; your editor contents are never uploaded. | web | Open tool |
| HTML to PDF Converter – Save Web Content as a PDF | Convert pasted HTML or an HTML file to PDF in your browser. Preview safely, choose page settings, and save a searchable PDF with no upload or account. | documents | Open tool |
| HTTP Status Code Checker & Reference | Check HTTP response codes from your browser and look up every registered 1xx, 2xx, 3xx, 4xx, and 5xx status with plain-English explanations. | web | Open tool |
| Hull Speed Calculator for Displacement Boats | Calculate displacement boat hull speed from waterline length in feet or meters. See knots, mph, km/h, Froude number, speed-length ratio, formulas, and limits. | marine | Open tool |
| Hyperfocal Distance Calculator | Calculate hyperfocal distance and near sharpness limit from focal length, aperture, and sensor format. Useful for landscape, street, and cinema focus. | studio | Open tool |
| Hypothesis Test Calculator — Z-Test, T-Test, P-Value & Critical Value | Calculate z-tests and t-tests for means and proportions. Get the test statistic, p-value, critical value, rejection region, and decision with formulas. | statistics-probability | Open tool |
| Ideal Gas Law Calculator (PV = nRT) | Solve PV = nRT for any variable with unit support for pressure, volume, and temperature. Includes Boyle, Charles, and Gay-Lussac two-state calculators. Client-side. | science | Open tool |
| Ideal Weight Calculator: Healthy Weight Range by Height and Sex | Estimate ideal body weight and healthy BMI range by height and sex. Includes Broca, Devine, Hamwi, Robinson, Miller, Lorentz, Peterson, current BMI context, and private browser-only calculations. | health | Open tool |
| Image Resizer & Converter — JPG, PNG, WebP, BMP, TIFF, GIF, ICO | Free, private image resizer & converter. Resize, convert (JPG, PNG, WebP, BMP, TIFF, GIF, ICO), and export without uploads. Everything runs locally in your browser. | graphics | Open tool |
| Image to Base64 Converter | Convert PNG, JPG/JPEG, GIF, WebP, SVG, ICO, and BMP images to raw Base64, Data URI, HTML, CSS, JSON, XML, favicon links, and more. Local files stay in your browser. | web | Open tool |
| Implicit Differentiation Calculator with Steps | Find dy/dx from an implicit equation with exact symbolic results, rule-by-rule steps, point evaluation, vertical-tangent checks, and private browser calculation. | calculus | Open tool |
| Improper Integral Convergence Calculator | Test improper integrals for convergence over infinite intervals or near singularities. See one-sided limits, value estimates, absolute convergence and cutoff evidence. | calculus | Open tool |
| Impulse and Momentum Calculator | Impulse and momentum calculator for p = mv, J = FΔt, change in momentum, average force, contact time, and 2D or 3D momentum vectors. | science | Open tool |
| Inclusion–Exclusion Principle Calculator | Calculate the union of 2 to 6 finite sets with inclusion–exclusion. Enter every intersection count and see exact terms, partial sums, and consistency checks. | discrete-mathematics | Open tool |
| Inequality Solver with Interval Notation and Number Line | Solve linear inequalities ax + b <, ≤, >, or ≥ cx + d with exact fractions, step-by-step work, interval notation, set-builder notation, and a number line. | algebra | Open tool |
| Inflation Calculator: Adjust Dollars by CPI from One Date to Another | Convert money between years with CPI. Enter an amount, choose U.S. CPI or UK CPIH dates, and see purchasing power, cumulative inflation, average annual rate, CPI values, and chart context. | finance | Open tool |
| Infrastructure Availability Calculator - Series, Parallel and Redundant Components | Calculate infrastructure availability for series, parallel, N+1, 2N and k-of-n redundant components, with expected downtime and block-by-block results. | infrastructure | Open tool |
| Insulation R-Value Calculator | Calculate layer-by-layer or whole-wall effective R-value with studs, climate target comparison, R/RSI/U-value conversions, presets, and shareable summaries. Client-side & private. | construction | Open tool |
| Integer Partition Calculator and Partition Generator | Calculate the exact partition number p(n) or generate every integer partition of n. View non-increasing sums, nearby values, and downloadable results. | number-theory | Open tool |
| Integral Calculator with Steps | Calculate indefinite and definite integrals with steps. Get symbolic antiderivatives, adaptive numerical fallback, bounds evaluation, verification and shaded graphs. | calculus | Open tool |
| Interactive Galton Board Probability Simulator | Run an interactive Galton board or bean machine simulation and compare observed bin counts with exact binomial probabilities and a normal approximation. | games | Open tool |
| Interest Rate Parity Calculator: Forward Exchange Rate from Spot and Interest Rates | Forward exchange rate calculator for covered interest parity. Enter spot rate, domestic and foreign interest rates, and time to calculate CIP, forward premium, implied rates, and UIP expected spot. | finance | Open tool |
| International Shoe & Clothing Size Converter | Convert adult shoe sizes and women’s or men’s clothing sizes between US, UK, EU, Japan and international labels. Includes measurement guidance and printable results. | calculators | Open tool |
| Inventory Break-Even Calculator – Units, Revenue and Contribution Margin | Calculate inventory break-even units and revenue, contribution margin per unit and ratio, target-profit units, and profit at expected sales. | finance | Open tool |
| Inventory Turnover Ratio Calculator | Calculate inventory turnover ratio, days sales of inventory, and average inventory from COGS plus beginning and ending inventory. Private browser-based tool. | logistics | Open tool |
| Inverse Function Calculator with Steps | Find inverse functions for linear, power, rational, exponential, and logarithmic forms. See domain and range restrictions, algebra steps, and a numerical check. | algebra | Open tool |
| Inverse Matrix Calculator with Gauss–Jordan Steps | Find the inverse of a 2×2 to 6×6 matrix with every Gauss–Jordan row operation. Paste a matrix, verify A·A⁻¹, then copy or download the steps. | linear-algebra | Open tool |
| Investment Goal Calculator | Investment goal calculator for monthly contributions, target date, final amount, starting balance, and required return. Includes fees, inflation, compounding, schedule, and tracker view. | finance | Open tool |
| IP Subnet Calculator: CIDR, Subnet Mask, Wildcard Mask, Host Range | Calculate CIDR, subnet masks, wildcard masks, host ranges, reverse subnet sizing, and child subnet splits for IPv4 and IPv6. Runs locally in your browser. | calculators | Open tool |
| IP Subnet Utilization Calculator and Address Tracker | Calculate IPv4 subnet utilization from CIDR, subnet mask, wildcard mask, IP range, or required hosts. Check usable hosts, broadcast address, host range, available IPs, and threshold headroom. | infrastructure | Open tool |
| IPsec VPN Throughput Calculator | Calculate IPsec ESP tunnel overhead, effective MTU, TCP MSS, encrypted WAN capacity, packets per second, and per-tunnel throughput for AES-GCM, ChaCha20-Poly1305, and AES-CBC. | infrastructure | Open tool |
| Irregular Polygon Area Calculator from Coordinates | Calculate irregular polygon area from ordered x,y coordinates. Get shoelace steps, perimeter, centroid, orientation, validation, and area unit conversions. | geometry | Open tool |
| Irrigation Run Time Calculator | Calculate sprinkler or drip irrigation run time from target inches of water, precipitation rate, GPM, catch-can results, rainfall, ET, and system efficiency. | agriculture | Open tool |
| Irrigation Runtime Calculator for Sprinklers and Drip Systems | Calculate irrigation runtime, sprinkler run time, drip watering minutes, weekly gallons or liters, and timer-ready schedules with rain adjustment. | agriculture | Open tool |
| ISO 286 Limits & Fits Calculator | Calculate ISO 286-style hole and shaft tolerances, upper/lower deviations, limits, clearance, interference, and transition fits for H7/g6, H7/h6, H8/f7, H7/p6 and more. Client-side and private. | science | Open tool |
| ISO Week Number Converter — Week ⇄ Date (Mon–Sun) | Convert any date to its ISO week number and year (ISO 8601) — and convert an ISO week back to a calendar date. Shows Monday–Sunday range, handles week 53 and New Year edge cases. Free, accurate, 100% in-browser. | time-date | Open tool |
| Jacobian Matrix Calculator with Steps | Calculate a symbolic Jacobian matrix for up to six functions and variables. Evaluate it at a point and see every partial derivative step. | calculus | Open tool |
| Jam and Jelly Pectin Calculator | Scale fruit, sugar, and pectin from a tested jam or jelly recipe. Plan separate batches, estimate yield, and avoid mixing incompatible pectin directions. | cooking | Open tool |
| JavaScript Regex Tester | Test and debug JavaScript regular expressions live. Highlight matches, inspect capture groups, preview replacements, explain patterns and copy production-ready code privately in your browser. | web | Open tool |
| Jet Lag Calculator and Recovery Planner | Use a jet lag calculator to estimate recovery days, eastbound or westbound direction, sleep timing, light exposure, caffeine cutoff, nap advice, and short-trip strategy. | time-date | Open tool |
| JSON Formatter & Validator Online | Format, validate, minify, and explore JSON online. Get exact line-and-column errors, safe repair previews, file input, and a searchable tree—all locally in your browser. | web | Open tool |
| JSON Schema Validator Online | Validate JSON data against a JSON Schema online. Supports draft 2020-12, 2019-09, and draft-07 with clear instance paths and private browser processing. | web | Open tool |
| JSON to YAML Converter | Validate and convert JSON to downloadable YAML locally in your browser. Includes precise errors, file import, formatting options, examples, and YAML to JSON. | web | Open tool |
| JWT Decoder Online – Decode and Verify JSON Web Tokens | Decode JWT headers and payloads instantly, inspect claims and expiration, and verify HS, RS, PS, and ES signatures. Decoding and verification inputs are processed locally. | web | Open tool |
| JWT Encoder & Generator — Create and Sign JSON Web Tokens Online | Generate and sign JWTs in your browser with HMAC, RSA, RSA-PSS, or ECDSA. Add registered claims, inspect every segment, and verify signatures locally. | web | Open tool |
| Karnaugh Map Simplifier for Boolean Expressions | Simplify 2, 3, or 4-variable Boolean expressions with an interactive Karnaugh map. Enter an expression or minterms, add don't-cares, and get minimal SOP and POS forms. | discrete-mathematics | Open tool |
| Kinetic and Potential Energy Calculator | Calculate kinetic energy, potential energy, mass, speed, height, gravity, and conservation of energy with unit conversions and worked solution steps. Client-side. | science | Open tool |
| Knots, Nautical Miles and Beaufort Scale Converter | Convert knots, mph, km/h, m/s and Beaufort force, or convert nautical miles, statute miles, kilometers, meters and feet. Free and private. | marine | Open tool |
| Kubernetes Cluster Capacity Planner: Pods, CPU, Memory and Node Count | Estimate Kubernetes worker node count from pod replicas, CPU and memory requests, allocatable node resources, DaemonSet overhead, headroom, growth, and failed-node reserve. | infrastructure | Open tool |
| Labor Productivity Calculator: Output per Hour, per Employee, and Cost per Unit | Calculate labor productivity as output divided by labor input. Find output per hour, revenue per hour, output per employee, cost per unit, and benchmark variance. | logistics | Open tool |
| Landed Cost Calculator: Import Duty, Tax & Cost Per Unit | Calculate import landed cost per unit with product cost, freight, insurance, customs duty, VAT/GST, brokerage, delivery, and margin analysis. | logistics | Open tool |
| Lawn Fertilizer Runoff Risk Calculator | Screen lawn fertilizer runoff risk from application rate, rain timing, soil condition, slope, turf cover, pavement cleanup, buffers, and distance to water. | environment | Open tool |
| Lawn Replacement Water Savings Calculator | Estimate outdoor water and bill savings from replacing lawn or high-water planting with native, regionally appropriate plants. Private, client-side calculator. | environment | Open tool |
| LCM and GCF Calculator with Steps | Find the LCM and GCF, GCD, or HCF of two or more integers with step-by-step work using Euclidean, prime factorization, listing, ladder, or formula methods. | number-theory | Open tool |
| LDAP / FILETIME Converter — 18-Digit Windows Timestamps ↔ Date | Convert LDAP, Active Directory and Windows FILETIME timestamps to dates and back. Supports 18-digit decimal, hex, scientific notation, UTC/local time, Unix time, and AD Never values. | time-date | Open tool |
| Lead Time Calculator: Supply Chain Stages and Delivery Date | Calculate procurement, production, shipping, and end-to-end supply chain lead time, delivery dates, bottlenecks, scenarios, and reorder outputs. | logistics | Open tool |
| Least Squares Regression Matrix Calculator | Fit a least-squares regression from a design matrix and response vector. Find coefficients, predictions, residuals, R-squared, RMSE, rank, and matrix steps. | linear-algebra | Open tool |
| LED Savings Calculator: LED vs Incandescent Cost & Payback | Calculate LED bulb savings, monthly and annual cost reduction, kWh saved, payback date, and lifetime net savings when replacing incandescent bulbs. | environment | Open tool |
| LEGO Brick Tower Calculator — How Many Bricks to Reach Any Height? | Calculate how many LEGO bricks or plates you need to reach any height. Choose metric or imperial units, set bricks per layer, and see the exact overshoot. | fun | Open tool |
| Lens and Mirror Equation Calculator | Free thin lens and spherical mirror equation calculator. Solve for image distance, object distance, focal length, magnification, image height, real/virtual image type, and upright/inverted orientation. | science | Open tool |
| Lens Diffraction Calculator | Calculate Airy disk diameter, diffraction cutoff, pixel coverage, sensor Nyquist frequency, and angular diffraction limit from aperture, wavelength, pixel pitch, and focal length. | studio | Open tool |
| Lens Equivalent Calculator | Convert focal length and aperture between full frame, APS-C, Micro Four Thirds, and medium format equivalents for matching field of view and depth of field. | studio | Open tool |
| Levenshtein Distance Calculator | Calculate Levenshtein edit distance and similarity between two strings. Includes visual diff, character or word mode, custom costs, DP matrix, examples, and private browser-side processing. | text | Open tool |
| Life Insurance Calculator: Estimate Cover and Term Cost | Estimate how much life insurance cover you may need, choose a suitable term, and explore an illustrative term-life cost range. Free, private and browser-based. | finance | Open tool |
| Lighting Inverse Square Law Calculator — Distance, Lux & Exposure Stops | Calculate light level in lux at a new distance, solve for distance from a target lux value, and see the change in exposure stops using the inverse square law. | studio | Open tool |
| Lime Requirement Calculator for Soil pH | Calculate how much lime to apply from soil pH or a lab recommendation. Get tons per acre, lb/1,000 sq ft, kg/ha, bag counts, cost, and application guidance. | agriculture | Open tool |
| Limit Calculator with Steps | Calculate two-sided, left-hand, right-hand and infinite limits with steps. Supports direct substitution, L’Hôpital’s rule, asymptotic analysis and DNE detection. | calculus | Open tool |
| Limiting Reagent / Limiting Reactant Calculator | Find the limiting reagent or limiting reactant from a balanced reaction, show excess reactant left over, and calculate theoretical product yield. Private, client-side chemistry tool. | science | Open tool |
| Line Intersection Calculator | Find the intersection point of two lines from equations or two points. Shows exact fractions, decimals, worked steps, graph preview, and segment checks. | geometry | Open tool |
| Linear Diophantine Equation Solver with Integer Solutions | Solve ax + by = c over the integers. Check whether solutions exist, find one exact solution and the complete parameterized family, and see GCD steps. | number-theory | Open tool |
| Linear Equation Solver with Step-by-Step Solutions | Solve ax + b = c with exact fractions, decimals, clear algebra steps, and substitution checks. Handles one solution, no solution, and infinite solutions. | algebra | Open tool |
| Linear Independence and Basis Calculator | Test vectors for linear independence, find a basis for their span, identify redundant vectors, and view RREF and dependence relations. | linear-algebra | Open tool |
| List Randomizer: Shuffle Names and Items Online | Paste names or items, choose shuffle or winners, remove duplicates if needed, then copy, print, or export the random order. Private client-side list randomizer with optional seeded results. | random | Open tool |
| Little Star Glider — Calm. Friendly. Private. | Guide a little ⭐ through gentle ☁️ cloud gaps. Simple tap-to-glide gameplay with smooth animation. 100% client-side, mobile-friendly, ad-light. | games | Open tool |
| Livestock Feed Conversion Ratio and Feed Cost Calculator | Calculate livestock feed conversion ratio, feed efficiency, cost of gain, bag duration, waste, dry matter, and feed cost per animal for cattle, pigs, poultry, goats, sheep, rabbits, and horses. | agriculture | Open tool |
| Livestock Water Requirement Calculator: Daily Needs & Tank Size | Calculate daily livestock water needs and practical reserve tank size for mixed cattle, dairy, horse, sheep, goat, pig, chicken, and turkey groups. | agriculture | Open tool |
| Load Balancer Sizing Calculator | Size load balancer nodes, AWS ALB LCUs, requests per second, concurrent connections, connection rate, throughput, zones, target utilization, and failover headroom. Private, client-side. | infrastructure | Open tool |
| Loan Calculator: Monthly Payment, Total Interest and Amortization Schedule | Calculate loan payment, total interest, payoff date, amortization schedule, extra payment savings, fees, and APR-style cost for fixed-rate loans. | finance | Open tool |
| Loan Comparison Calculator: Compare Two Loans Side by Side | Compare loan offers side by side with APR, fees, extra payments, total cost, payoff dates, charts, and full amortization schedules. Private—runs in your browser. | finance | Open tool |
| Log Calculator (Logarithm Calculator) | Log calculator for log_b(x)=y. Solve for x, base b, or y with ln, log10, log2, any base, antilog, worked steps, examples, and a graph. | algebra | Open tool |
| Log Storage Calculator | Calculate log storage from ingestion rate, retention, compression, replicas, index overhead, and free-space headroom. See daily volume and decimal and binary capacity estimates. | infrastructure | Open tool |
| Logical Equivalence Checker with Truth Tables | Check whether two propositional logic formulas are logically equivalent. Compare complete truth tables, find counterexamples, copy results, or download CSV. | discrete-mathematics | Open tool |
| Lorem Ipsum Generator — Words, Sentences & Paragraphs | Free Lorem Ipsum generator for words, sentences, paragraphs, HTML and Markdown. Create private, repeatable placeholder text in your browser and copy or download instantly. | web | Open tool |
| Love Calculator by Name | Enter two first names, nicknames, or full names to get a 0-100% love match score. Optional birthdays, private in-browser calculation, and just for fun. | fun | Open tool |
| Low-Flow Toilet Water Savings Calculator | Estimate water and bill savings from replacing an older toilet with a low-flow or dual-flush model. Includes costs, rebates, payback, gallons and litres. | environment | Open tool |
| LU Decomposition Calculator with Step-by-Step Matrices | Calculate a pivoted LU decomposition online. See P, L, and U matrices, every row swap and elimination step, the determinant, and a reconstruction check. | linear-algebra | Open tool |
| LUFS Loudness Normalization Calculator — Streaming Platform Targets | Calculate LUFS normalization gain and peak-safe playback loudness for Spotify, Apple Music, YouTube, Amazon Music, TIDAL, Deezer, EBU R128, or a custom target. | studio | Open tool |
| Lumber Board Feet Calculator | Calculate board feet (FBM) for mixed lumber orders with multiple boards, units, nominal sizes, waste factor, MBF, cubic feet, and estimated cost. | construction | Open tool |
| Mac HFS+ Timestamp Converter - HFS Plus Seconds Since 1904 | Convert Mac HFS+ timestamps, HFS Plus timestamp values, and Mac OS Extended seconds since January 1, 1904 GMT/UTC to dates. Includes current timestamp, hex, endian, and batch decoding. | time-date | Open tool |
| Macro Magnification Calculator — Extension Tubes, Focal Length & Working Distance | Calculate extension-tube magnification, reproduction ratio, estimated working distance, subject field width, target extension, and effective aperture from lens focal length. | studio | Open tool |
| Make-or-Buy Decision Calculator | Run a make vs buy analysis for in-house vs supplier, outsourcing decisions, fixed and unit costs, scrap yield, and break-even volume. Private, browser-based. | logistics | Open tool |
| Manure Application Rate Calculator: Tons or Gallons per Acre | Calculate manure application rates from crop N, P2O5, and K2O needs, manure analysis, first-year availability, field area, and solid or liquid units. | agriculture | Open tool |
| MAPE Calculator (Mean Absolute Percentage Error) | Calculate MAPE, MAE, WAPE, forecast bias, best and worst period error, and per-period APE from actual and forecast demand series. Client-side only. | logistics | Open tool |
| Margin of Error Calculator — Sample Size & Confidence Level | Calculate margin of error or required sample size for a proportion or mean. Supports custom confidence levels and finite population correction. | statistics-probability | Open tool |
| Marina Berth Size and Clearance Calculator | Check whether a marina berth fits your boat's length, beam, draft, and optional air draft using your chosen end, side, under-keel, and overhead clearances. | marine | Open tool |
| Marinade Calculator | Calculate marinade amount by meat weight and estimate marinating time for beef, pork, poultry, fish, and shellfish. Includes cups, mL, safe handling, copy, and download. | cooking | Open tool |
| Marine Corrosion and Sacrificial Anode Sizing Calculator | Estimate marine sacrificial-anode current demand, amp-hours, required alloy mass, whole-anode count, installed capacity, and modeled service life. | marine | Open tool |
| Marine Electrical Wire Size and Voltage Drop Calculator | Calculate marine DC copper wire size and voltage drop from volts, amps, cable length, insulation rating, engine-space heat, and conductor bundling. | marine | Open tool |
| Marine Engine Propulsive Efficiency Calculator | Calculate marine propulsive efficiency, effective power, required engine or propeller power, vessel resistance, or speed from resistance-times-speed power. Supports marine and SI units. | marine | Open tool |
| Marine Fuel Tank Capacity Calculator | Calculate marine fuel tank capacity from rectangular, cylindrical, or elliptical tank dimensions in inches, feet, metric units, US gallons, liters, or Imperial gallons. | marine | Open tool |
| Marine Holding Tank Capacity and Pump-Out Planner | Estimate a marine holding tank's capacity, days to a chosen fill limit, trip margin, pump-out volume, and optional pump-out time using private browser calculations. | marine | Open tool |
| Marine Navigation Distance and Bearing Calculator | Calculate great-circle and rhumb-line distance and true bearing between two latitude/longitude positions, with nautical, metric, and statute units. | marine | Open tool |
| Markdown Table Builder — Edit, Preview & Copy GFM Tables | Build Markdown tables visually: edit cells, paste CSV/TSV data, set per-column alignment, preview rendered output, and copy GFM syntax. 100% client-side and private. | web | Open tool |
| Markdown to HTML Converter | Convert Markdown files or pasted text to semantic HTML with live GFM preview, safety controls, themes, and fragment or complete-document downloads. Private and local. | web | Open tool |
| Markov Chain Calculator & Simulator | Markov chain calculator and simulator for transition matrices, P^n, pi0 P^n, stationary distribution, random walks, diagnostics, charts, and export. Client-side and private. | statistics-probability | Open tool |
| Markup and Margin Calculator | Calculate selling price, gross profit, markup, and margin from any two values, including advanced costs, discounts, rounding, and tax display. | finance | Open tool |
| Mass-Spring Oscillator Calculator (SHM) — Period, Frequency & Energy | Solve a mass-spring oscillator forward or backward for period, natural frequency, angular frequency, spring constant, mass, force, amplitude, or energy with unit conversion and steps. | science | Open tool |
| Master Theorem Recurrence Complexity Calculator | Solve T(n) = aT(n/b) + Θ(n^k(log n)^p) with a Master Theorem calculator that identifies the case and explains the asymptotic result. | discrete-mathematics | Open tool |
| Matrix Calculator | Add, multiply, or transpose matrices up to 8×8. Paste matrix values, see dimension checks and calculation steps, then copy or download results privately in your browser. | linear-algebra | Open tool |
| Matrix Condition Number Calculator | Calculate a matrix condition number in the 2, 1, infinity, or Frobenius norm. Inspect singular values, estimated rank, inverse, and potential error amplification. | linear-algebra | Open tool |
| Matrix Diagonalization Calculator with Steps | Diagonalize a 2×2 or 3×3 matrix as A = PDP⁻¹. Find eigenvalues, eigenvectors, P, D, P⁻¹, defect tests, and verification steps. | linear-algebra | Open tool |
| Matrix Rank and Nullity Calculator | Calculate a rectangular matrix's rank and nullity from RREF. Find pivot and free columns, plus bases for the null, column, and row spaces. | linear-algebra | Open tool |
| Maze — Calm, Playable, Privacy-First | Play a calm, mobile-friendly maze game. Swipe or use the D-pad to guide the dot to the star. Seeded generator, hints, crumb trail, and gentle colors. 100% client-side. | games | Open tool |
| Mean, Median, Mode, Range Calculator | Calculate mean, median, mode, range, quartiles, IQR, and outliers with visible steps. Paste numbers from spreadsheets or homework lists. | statistics-probability | Open tool |
| Meat Thawing Time Calculator | Meat thawing time calculator for beef, pork, chicken, turkey, and fish. Compare refrigerator and cold-water defrost times by weight and cut. | cooking | Open tool |
| Meeting Time Finder and Time Zone Meeting Planner | Meeting time finder and time zone meeting planner for global calls. Choose cities, work hours, duration, and date range to rank the best shared meeting windows. | time-date | Open tool |
| Merge PDF Files Online for Free | Merge multiple PDF files into one instantly—free, private, and 100% in your browser. Reorder, remove, and download the combined PDF with no uploads. | documents | Open tool |
| Microphone Sensitivity Calculator — dBV/Pa ↔ mV/Pa | Convert microphone sensitivity between dBV/Pa and mV/Pa. Quickly see how hot a mic is and match it with your interface gain—100% client-side. | studio | Open tool |
| Microwave Cooking Time Converter by Wattage | Convert microwave cooking times between 300 and 3000 watts. Enter a recipe time, recipe wattage, and your microwave wattage for a clear time estimate. | cooking | Open tool |
| MIDI Note to Frequency Calculator — Notes, Hertz & Cents | Convert MIDI note numbers and note names to frequency, or Hz to the nearest MIDI note and cents offset. Supports custom A4 tuning, sharps, flats, copy, and CSV. | studio | Open tool |
| Midpoint Calculator | Free Midpoint Calculator: find the midpoint between two coordinates in 2D or 3D: M = ((x₁+x₂)/2, (y₁+y₂)/2[, (z₁+z₂)/2]). Fast, private, and 100% client-side. | geometry | Open tool |
| Minimum Credit Card Payment Calculator | Estimate your minimum credit card payment, payoff date, total interest, and savings from paying extra using common card issuer formulas. | finance | Open tool |
| Minimum Spanning Tree Calculator — Kruskal and Prim Visualizer | Calculate a minimum spanning tree with Kruskal’s or Prim’s algorithm. Visualize accepted and rejected edges, total weight, and every greedy step. | discrete-mathematics | Open tool |
| Modular Arithmetic Calculator | Check modular congruence, find modular inverses with the extended Euclidean algorithm, and calculate large modular powers with exact integer arithmetic. | discrete-mathematics | Open tool |
| Molality Calculator | Client-side molality calculator for finding molality, solute mass, solute moles, or solvent mass in mol/kg. Includes chemistry formulas, examples, copy/download controls, and clear validation. | science | Open tool |
| Molarity Calculator — Mass • Volume • Concentration | Calculate molarity, mass, volume, molecular weight, stock dilution, or molarity from g/L, ppm, ppb, and % w/v. Shows worked steps instantly. | calculators | Open tool |
| Molecular Weight Calculator (Molar Mass) | Calculate molar mass from chemical formulas such as H2O, CO2, NaCl, glucose, hydrates, and formulas with parentheses or brackets. Includes protein, DNA, and RNA mass modes. | science | Open tool |
| Moles to Grams and Gas Volume Calculator | Convert grams, moles, and gas volume at STP, IUPAC STP, SATP, or custom temperature and pressure. Includes formula molar mass, flexible units, and worked steps. | science | Open tool |
| Mortgage Closing Costs Calculator – Estimate Cash Needed at Closing | Estimate mortgage closing costs and cash needed at closing from loan costs, prepaids, escrow, down payment, deposits, financed costs, and credits. | finance | Open tool |
| Mortgage Points Calculator: Compare Discount Points and Break-Even | Compare a zero-point mortgage with a discount-points offer. Calculate point cost, monthly savings, two break-even measures, and savings over your planned holding period. | finance | Open tool |
| Mortgage Refinance Break-Even Calculator: Is Refinancing Worth It? | Compare a current mortgage with up to three refinance offers. Estimate cash-flow and economic break-even, payment changes, and net savings over your planned holding period. | finance | Open tool |
| Mortgage Repayment Calculator: Monthly Payments, Interest, and Amortization | Calculate mortgage repayments, deposit and loan amount, total interest, payoff date, housing costs, overpayments, and an amortization schedule. Runs in your browser. | finance | Open tool |
| Mouse Sensitivity Converter & ADS FOV Calculator | Convert mouse sensitivity between Valorant, CS:GO/CS2, Overwatch 2, Apex, Call of Duty, Rainbow Six Siege, Fortnite, Rust, and Destiny 2. Get cm/360, eDPI, and focal-length ADS values. | studio | Open tool |
| MTU, TCP MSS and VPN Overhead Calculator | Calculate effective MTU, TCP MSS, UDP payload, Ethernet wire overhead, VLAN tags, VPN tunnel overhead, VXLAN, GRE, PPPoE, and jumbo frame sizing. Private, client-side. | infrastructure | Open tool |
| Möbius Function and Mertens Function Calculator | Calculate the Möbius function μ(n) and Mertens function M(n) with prime factorization, square-free classification, summatory counts, and exact steps. | number-theory | Open tool |
| Natural Frequency and Resonance Calculator | Calculate or solve for natural frequency, mass, stiffness, inductance, capacitance, RLC resonance, Q and bandwidth with unit conversion, steps and response plots. | science | Open tool |
| ND Filter Calculator | Calculate ND filter strength in stops, filter factor, and optical density from current and target shutter speeds. Private browser-based tool. | studio | Open tool |
| Nernst Equation Calculator: Cell EMF, Q, and K | Calculate electrochemical cell potential with the Nernst equation, solve for reaction quotient Q, estimate equilibrium constant K from E°, or evaluate concentration cells. Client-side and private. | science | Open tool |
| Net Income Calculator | Calculate business net income after tax from revenue, COGS, operating expenses, interest, non-operating items, and tax rate. Includes steps and profit margin. | finance | Open tool |
| Net Worth Calculator – Assets, Liabilities and Financial Progress | Calculate net worth from itemized assets and liabilities, compare it with an earlier snapshot, and download a private financial progress summary. | finance | Open tool |
| Network Bandwidth Calculator and Throughput Capacity Planner | Free network and internet bandwidth calculator. Estimate required download and upload Mbps or Gbps by users, workloads, concurrency, overhead, and utilization, then choose a circuit size. | infrastructure | Open tool |
| New vs Used Car Total Cost Calculator | Compare new vs used car total cost over 5 years: depreciation, loan interest, fuel, insurance, fees, maintenance, repairs, tires, resale and monthly cost. | finance | Open tool |
| Normal Distribution Calculator — CDF, Probability & Critical Values | Calculate normal distribution CDF, upper-tail and interval probabilities, z-scores, density, percentiles, and one- or two-sided critical values. | statistics-probability | Open tool |
| Normality Calculator | Calculate normality (N or eq/L) from solute mass, equivalent weight and volume, convert molarity, prepare solutions, or solve for any missing variable. | science | Open tool |
| NPK Fertilizer Mixing Calculator | Calculate fertilizer application rates, total weight, bags, cost, and practical N-P2O5-K2O blends from common fertilizer grades. | agriculture | Open tool |
| NPV & IRR Calculator | Calculate NPV, IRR, XNPV, XIRR, MIRR, profitability index and payback for regular or dated cash flows, with interpretation and a full calculation audit. | finance | Open tool |
| NTP Offset, Delay and Clock Drift Calculator | Calculate NTP clock offset from timestamps, estimate oscillator drift between syncs, and size a safe sync interval against an offset tolerance. Private, client-side. | infrastructure | Open tool |
| Null Space and Column Space Calculator | Find bases and dimensions for a matrix's null space and column space. See RREF, pivot and free columns, verification, and clear calculation steps. | linear-algebra | Open tool |
| Number Base Converter: Binary, Decimal, Hex & Octal | Convert binary, decimal, hexadecimal, and octal instantly. Supports BigInt integers, prefixes, 4-bit binary grouping, copy buttons, and private in-browser conversion. | calculators | Open tool |
| Object Storage Cost Calculator: Capacity, Requests, Retrieval and Egress | Calculate object storage cost from capacity, read and write requests, data retrieval, egress, free transfer allowance, and your provider's rates. | infrastructure | Open tool |
| OBS Video Bitrate Calculator | Calculate OBS-ready video bitrate in kbps for Twitch, YouTube Live, Kick, Facebook Live, and TikTok Live by platform, codec, upload speed, content type, and headroom. | studio | Open tool |
| Octane Mixing Calculator | Calculate the amounts of two fuels needed for a target octane, how much fuel to add, or the estimated octane of a known blend. Supports AKI, RON, and MON. | automotive | Open tool |
| Odds and Probability Converter | Convert decimal, fractional, and American moneyline odds to implied probability. See formulas, fair odds, and optional stake returns instantly. | statistics-probability | Open tool |
| Ohm’s Law Calculator | Enter any two values (V, I, R, P) to instantly compute the other two. Ohm’s law and power equations with unit converters—100% private, runs in your browser. | calculators | Open tool |
| Oil Change Interval Calculator | Calculate an oil change deadline by mileage and date using your vehicle's normal or severe-service schedule. See distance remaining, time remaining, and due status. | automotive | Open tool |
| One Rep Max Calculator (1RM) — Estimate Your Maximum | Estimate your one rep max from a hard set, compare three formulas, and calculate practical training loads in kg or lb. | health | Open tool |
| Online Countdown Timer with Alarm | Set a free online countdown timer for hours, minutes, or seconds. Start instantly, choose an alarm, pause or repeat it, and use fullscreen mode—no download or sign-up. | time-date | Open tool |
| Online Hash Generator and Checksum Calculator | Generate text and file hashes locally in your browser. Supports MD5, SHA-1, SHA-256, SHA-512, SHA-3, CRC32, Adler32, HMAC, encodings, checksum comparison, and copyable output. | web | Open tool |
| Online JavaScript Minifier & Beautifier — JS Compressor and Formatter | Minify, compress, beautify, format, or unminify JavaScript online with Terser and js-beautify. Local browser processing, syntax diagnostics, file upload, and exact size metrics. | web | Open tool |
| Online Stopwatch with Lap Timer, Splits & Fullscreen | Free online stopwatch with lap timer, split times, fullscreen mode, keyboard shortcuts, CSV export, and privacy-first browser timing. No download or sign-up. | time-date | Open tool |
| Online Whiteboard & Drawing Tool (Private, No Uploads) | Free online whiteboard — no account, no uploads, nothing stored. Draw in your browser, export PNG. No Miro account required, no sign-up, works instantly and privately. | graphics | Open tool |
| Open Graph Meta Tag Generator and Social Preview Tool | Generate ready-to-paste Open Graph and Twitter/X tags with live platform previews, HTML import, image checks, and validation. Free, private, and no signup. | web | Open tool |
| Optimization Calculator: Find Maximum and Minimum Values | Find maximum and minimum values with calculus steps, exact expressions where supported, derivative sign charts, open or infinite domains, applied templates, and a graph. | calculus | Open tool |
| Orchard Spacing Calculator: Trees per Acre & Tree Count | Calculate trees per acre or hectare, total orchard trees, rows, trees per row, pollinizers, service alleys, and nursery order quantities. | agriculture | Open tool |
| Order Picking Time Calculator | Calculate order picking time, daily pick hours, FTE staffing, walk time, and labour cost from orders, lines per order, pick rate, and shift length. Free browser-based warehouse calculator. | logistics | Open tool |
| Outlier Calculator — IQR, Z-Score & Modified Z-Score Methods | Find potential outliers using IQR fences, z-scores, and modified z-scores. Compare methods, inspect every value, and download results privately. | statistics-probability | Open tool |
| Oven Temperature Converter & Conversion Chart (°C, °F, Fan and Gas Mark) | Convert oven temperatures between Celsius, Fahrenheit, fan or convection ovens, and gas marks. Choose practical recipe settings or exact formula conversions. | cooking | Open tool |
| Packets Per Second Calculator | Calculate Ethernet packets per second (PPS and Mpps) from bandwidth and frame size, including VLAN, preamble, SFD, FCS and inter-frame gap overhead. | infrastructure | Open tool |
| Paint, Flooring and Tile Coverage Calculator | Calculate how much paint, flooring or tile to buy. Estimate litres or US gallons, tins, flooring packs, tiles, boxes, waste and cost for one or multiple rooms. | construction | Open tool |
| Pallet Calculator: How Many Boxes Fit on a Pallet? | Calculate how many boxes, cases, or cartons fit on a pallet. Optimize TI-HI, mixed layer patterns, stack height, weight, overhang, and pallets required. | logistics | Open tool |
| Paper Savings Calculator — Trees, CO₂, Water, Energy and Cost Saved | Estimate sheets, trees, CO₂e, water, energy and cost saved by going paperless. Model partial reductions, paper types, office sizes and digital use. | environment | Open tool |
| Parallel and Perpendicular Line Calculator — Equations Through a Point | Find exact parallel and perpendicular line equations through a point. Enter a source line by slope, standard form, or two points and see steps and a graph. | geometry | Open tool |
| Parallelogram Calculator — Area, Perimeter, Height and Diagonals | Calculate parallelogram area, perimeter, perpendicular heights, diagonals and angles from two sides and an angle, or from a base, side and height. | geometry | Open tool |
| Parasitic Battery Drain Calculator | Estimate how long a parasitic current draw may take to discharge a vehicle battery, or infer average draw from elapsed time, battery capacity, and charge limits. | automotive | Open tool |
| Partial Derivative Calculator with Steps | Calculate first, higher-order, and mixed partial derivatives with exact symbolic results and rule-by-rule steps. Evaluate at a point, copy, or download the work. | calculus | Open tool |
| Partial Fraction Decomposition Calculator | Enter a rational function and get its partial fraction decomposition with exact or approximate coefficients, complete algebra steps, and verification. | algebra | Open tool |
| Particle in a Box Calculator: 1D Schrödinger Equation Solver | Free particle in a box calculator for the 1D infinite square well. Calculate energy levels, wavelengths, nodes, wavefunctions, and probability density. | science | Open tool |
| Party Food Calculator – Portions and Quantities for a Crowd | Calculate party food quantities for adults and children, including pizza, tacos, sliders, appetizers, snacks, dip, produce, desserts, drinks, and ice. | cooking | Open tool |
| Password Strength Checker — Test How Secure Your Password Is | Test password strength with a private, client-side checker. Heuristic score, entropy estimate, common-pattern warnings, and optional PBKDF2 timing via WebCrypto. | web | Open tool |
| Pasta Serving Calculator – Dry Pasta, Water & Portions | Calculate dry pasta per person, portions, cooking water, pot size and estimated cooked yield. Plan by diners or by pasta weight in grams, ounces or pounds. | cooking | Open tool |
| Pasture Stocking Rate Calculator | Calculate cows or livestock supported, acres per head, grazing days, Animal Unit Months (AUM), and pasture carrying capacity from forage dry matter. | agriculture | Open tool |
| Patch Panel Calculator: How Many Ports and Panels Do You Need? | Calculate how many patch panels and ports you need from cable drops, reserve capacity, and panel size. Compare 12-, 24-, 48-, and 96-port panels, switch counts, and rack space. | infrastructure | Open tool |
| Paver Base Calculator: Gravel, Sand and Paver Quantity | Calculate paver base gravel, bedding and joint sand, paver quantity, edge restraint, geotextile, weights, bags, order overage, and optional costs. | construction | Open tool |
| Payback Period Calculator | Calculate simple and discounted payback periods for equal or uneven annual or monthly cash flows, with currency choice, target testing, and clear workings. | finance | Open tool |
| PCR Primer Tm, GC Content & Annealing Temperature Calculator | Analyze a forward and reverse PCR primer pair: SantaLucia nearest-neighbor Tm with Owczarzy salt correction, GC content, annealing temperature, dimers, hairpins, quality grading, and export. | science | Open tool |
| PDF Metadata Remover – Clear Author, Title and Document Properties | Remove PDF author, title, subject, keywords, dates, custom properties and XMP metadata locally in your browser. Free, private and no upload. | documents | Open tool |
| PDF Paper Size Converter – Resize Pages to A4, Letter or Legal | Resize PDF pages to A4, US Letter, Legal or a custom size online. Fit or fill pages privately in your browser, then download without upload or watermark. | documents | Open tool |
| PDF to Image Converter – Convert PDF to JPG or PNG Free | Convert every or selected PDF pages to separate JPG or PNG images free. Private browser processing, ZIP download, no signup, and no watermark. | documents | Open tool |
| PDF to Text Converter | Convert searchable PDFs to text in your browser. Extract selectable PDF text online, copy results, and download TXT, CSV, or JSON with no upload or account. | documents | Open tool |
| PDU Load Calculator | Calculate rack PDU load, amps, VA, growth reserve, 80% circuit capacity, breaker size, and A/B redundancy failover from watts, equipment, or measured current. | infrastructure | Open tool |
| Peak Flow Zone Calculator | Calculate green, yellow, and red asthma peak flow zones from your personal best. Optionally classify a current reading. Private and client-side. | health | Open tool |
| Pell Equation Solver for Integer Solutions | Solve x² − Dy² = 1 over the integers. Find the fundamental solution, continued fraction of √D, exact verification, and the first positive solutions. | number-theory | Open tool |
| Per Diem & Travel Budget Calculator | Estimate a travel budget from per diem allowance, meals and incidentals, lodging nights, taxes, transportation, and other trip costs. Runs privately in your browser. | logistics | Open tool |
| Percent Composition Calculator | Calculate percent composition by mass from a chemical formula. Get molar mass, element counts, element masses, and mass percentages instantly in your browser. | science | Open tool |
| Percent Yield Calculator — Actual and Theoretical Yield | Percent yield calculator and percentage yield calculator for actual yield, theoretical yield, reaction efficiency, yield loss, and clear step-by-step working. | science | Open tool |
| Percentage Calculator | Calculate percentages, increases, decreases, reverse percentage changes, percentage change, and percentage difference with formulas and steps. | finance | Open tool |
| Percentage Change Calculator | Calculate percentage change, increase, or decrease from an initial value to a final value. Instantly solve for a missing value and see the full calculation. | finance | Open tool |
| Percentile Calculator — Rank, Quartiles & Percentile Values | Calculate percentile rank, any percentile value, Q1, median, Q3, and IQR from a number list. Choose tie and interpolation methods and see the steps. | statistics-probability | Open tool |
| Perfect Order Rate Calculator: Formula, Example & Benchmarks | Calculate actual perfect order rate or a four-component Perfect Order Index. Includes formulas, examples, benchmarks, definitions, and target scenarios. | logistics | Open tool |
| Perfect, Abundant and Deficient Number Checker | Check whether a positive integer is perfect, abundant, or deficient. See its proper divisors, exact divisor sum, prime factorization, and steps. | number-theory | Open tool |
| Permeable Pavement Runoff & Storage Calculator | Evaluate permeable pavement runoff capture or size pavement area and stone reservoir depth for a design storm. Estimate overflow, loading ratio, slope-adjusted storage, and drawdown. | environment | Open tool |
| Permutation and Combination Calculator | Calculate and compare nPr and nCr, choose the right counting rule, and solve permutations, combinations, reusable choices, and repeated-letter arrangements. | discrete-mathematics | Open tool |
| Perpendicular Bisector Calculator from Two Points | Find the perpendicular bisector of two points. Get the midpoint, exact line equation, slope, graph, and step-by-step solution for decimals or fractions. | geometry | Open tool |
| Perpetuity Calculator | Calculate the present value of a level or growing perpetuity, compare discount and growth assumptions, or estimate Gordon Growth terminal value. | finance | Open tool |
| Personal Water Footprint Calculator | Estimate direct household water and hidden water from diet and selected purchases. See daily and annual household and per-person totals, benchmarks, and personalized savings. | environment | Open tool |
| Pet Insurance Calculator: Estimate Dog or Cat Costs | Estimate UK dog or cat insurance costs by breed, age, area and cover type, then test an eligible vet bill, excess, co-pay and policy limit. | finance | Open tool |
| pH / pOH Calculator | Convert between pH, pOH, hydrogen ion concentration, and hydroxide ion concentration. Includes optional pKw adjustment and private client-side calculations. | science | Open tool |
| Photon Energy, Wavelength & Frequency Calculator | Calculate photon energy, wavelength, frequency, eV, wavenumber, and kJ/mol. Includes unit conversions, steps, presets, and a full electromagnetic spectrum. | science | Open tool |
| Pipe Flow Calculator — Flow Rate, Velocity, Reynolds Number & Pressure Drop | Calculate pipe flow rate, velocity, Reynolds number, Darcy friction factor, head loss, and pressure drop with unit conversion, fluid presets, and pipe roughness presets. | science | Open tool |
| Pixel Pitch Calculator | Calculate camera sensor pixel pitch, megapixels, pixel area, sensor diagonal, pixels per millimetre, PPI, and megapixels per square centimetre from sensor size and resolution. | studio | Open tool |
| Plane Equation Calculator From Three Points | Enter three 3D points to get an exact simplified plane equation, normal vector, personalized steps, alternate forms, verification, and an interactive 3D view. | geometry | Open tool |
| Plant Population Calculator: Plants per Acre, Hectare & Seeding Rate | Calculate plants per acre or hectare from spacing, find seed rate for a target stand, estimate seed weight and bags, or check an emerged field stand. | agriculture | Open tool |
| Plastic Footprint Calculator: Estimate Your Annual Plastic Use | Enter everyday bottles, bags, packaging, toiletries, takeaway items, and household products. Get an annual plastic-use estimate, source breakdown, disposal-pathway estimate, and personalized reduction scenarios in a few minutes. | environment | Open tool |
| Play 3D Tic Tac Toe Online — 3×3×3 vs Computer | Play free 3D Tic Tac Toe online now on a 3×3×3 board. No download; mobile-friendly browser play versus the computer or a friend, with all 49 winning lines. | games | Open tool |
| Play Flagsweeper Online - Free Minesweeper Game | Play Flagsweeper online, a free browser Minesweeper-style game with Beginner, Intermediate, Expert, custom boards, first-click safety, mobile flag mode, and no download. | games | Open tool |
| Play Free Sudoku Online | Play free Sudoku online instantly. Choose Easy, Medium, Hard, or Expert puzzles, try today's daily Sudoku, use logical hints, notes, undo, and saved progress. | games | Open tool |
| Play Tic Tac Toe Online | Play Tic Tac Toe online free against the computer or with 2 players on the same device. Start instantly—no download, account, or sign-up. | games | Open tool |
| Plywood & OSB Sheathing Calculator: How Many Sheets Do I Need? | How many plywood or OSB sheets do you need? Total walls, roofs, subfloors and gables, then estimate 4x8 sheets, waste, cost, weight, nails and roof clips. | construction | Open tool |
| Podcast File Size Calculator — Duration, Bitrate & Episode Storage | Calculate podcast file size from episode duration and bitrate. Estimate one episode, a full library, monthly uploads, annual storage, and episodes per storage budget. | studio | Open tool |
| PoE Power Budget Calculator with Voltage Drop | Check PoE switch capacity, ports, class allocation, cable loss, and voltage at each powered device with peak-load and long-run planning. | infrastructure | Open tool |
| Pollinator Garden Size and Plant Planner | Plan a pollinator garden bed, estimate plant capacity or required area, and balance plant groups across spring, summer, and fall bloom. Free and private. | environment | Open tool |
| Polygon Angle Calculator – Interior & Exterior Angles | Find polygon interior and exterior angles, angle sums, missing angles, or the number of sides. Includes regular, irregular, and coordinate modes. | geometry | Open tool |
| Polygon Centroid Calculator from Coordinates | Calculate a polygon centroid from ordered x,y coordinates. Validate concave polygons, view the area-weighted center, formula steps, area, orientation, and an SVG preview. | geometry | Open tool |
| Polynomial Factoring Calculator with Steps | Factor polynomials in x with exact rational arithmetic. Extract the GCF, find repeated factors and rational zeros, and see synthetic-division steps. | algebra | Open tool |
| Polynomial Long Division Calculator with Steps | Divide polynomials in x with exact fractions. See every divide, multiply, subtract, and bring-down step, plus quotient, remainder, and verification. | algebra | Open tool |
| Polynomial Root Calculator — Real and Complex Zeros with Steps | Find every real and complex zero of a polynomial up to degree 10. Enter coefficients to see multiplicities, rational-root steps, numerical steps, and checks. | algebra | Open tool |
| Pool Evaporation & Water Loss Calculator | Calculate pool evaporation volume, rain offset, cover savings, refill cost, or compare pool and bucket-test water loss. Free and private. | environment | Open tool |
| Pool Volume Calculator: How Many Gallons or Litres Is My Pool? | Estimate pool water volume in US gallons, Imperial gallons and litres for rectangular, round, oval, kidney, triangular, L-shaped and custom pools. | construction | Open tool |
| Popcorn Expansion Calculator — Kernels to Bowls, Buckets and Bathtubs | Convert popcorn kernels into popped cups, bowls, cinema buckets and bathtubs—or work backwards. Adjust yield and expansion assumptions. Private and client-side. | fun | Open tool |
| Population Growth Calculator and Simulator: Exponential vs Logistic | Calculate future population, growth rate, carrying capacity, or target time. Compare exponential and logistic population growth with equations, steps, chart, and table. | science | Open tool |
| Portfolio Expense Ratio Calculator | Calculate a portfolio’s weighted expense ratio, estimated annual fund fees, and long-term investment cost from fund allocations or market values. | finance | Open tool |
| Portfolio Rebalancing Backtest Calculator | Backtest buy-and-hold, calendar, threshold, and calendar-plus-threshold portfolio rebalancing using ready historical data or your own CSV. | finance | Open tool |
| Portfolio Return Calculator | Calculate weighted portfolio return, holding contributions, total gain, CAGR, and money-weighted return (XIRR) with dated cash flows and benchmark comparison. | finance | Open tool |
| Post Hole Concrete Calculator for Fence & Deck Posts | Calculate bags per post and total bags for fence, gate, mailbox, and deck post holes, including gravel depth, post displacement, waste, volume, and cost. | construction | Open tool |
| Power Merge to 2048 — Simple. Smooth. Private. | Play 2048 in your browser with smooth animations, undo, and best score. 100% private and client-side. Mobile-friendly and ad-light. | games | Open tool |
| Power Set Calculator | Generate the complete power set of up to 15 unique elements. Filter subsets by size, copy results, and download CSV—all privately in your browser. | discrete-mathematics | Open tool |
| PPM and PPB Concentration Calculator | Calculate ppm, ppb, mg/L, ug/L, percent, and mass fraction for dilute solutions. Convert solute amount and sample volume or mass entirely in your browser. | science | Open tool |
| Pregnancy Due Date Calculator: How Many Weeks Pregnant Am I? | Estimate your due date and how many weeks pregnant you are using LMP, conception, IVF, ultrasound, or a clinical due date. | time-date | Open tool |
| Present Value Calculator | Free present value calculator for discounting future amounts and recurring contributions with APY or APR, compounding frequency, inflation context, copyable results, and CSV schedules. | finance | Open tool |
| Pressure Cooker Time Converter – Stovetop, Oven & Slow Cooker | Convert pressure-cooker time to practical stovetop, covered-oven, and slow-cooker starting ranges. Includes total elapsed time, release timing, food-safety checks, and clear assumptions. | cooking | Open tool |
| Prime Factorization Calculator | Find prime factors, exponent form, a factor tree, divisors, factor pairs, and trial-division steps for whole numbers up to 1 trillion. | number-theory | Open tool |
| Prime Number Generator and Sieve Calculator | Generate every prime in a range up to 10 million with an interactive Sieve of Eratosthenes. Copy or download exact results and view prime statistics. | number-theory | Open tool |
| Primer Tm Calculator for DNA/RNA Oligos | Calculate primer and oligo Tm for DNA/RNA using Wallace, GC% and nearest-neighbor methods. Adjust salt, Mg²⁺, concentration, DMSO and formamide, then get GC%, primer QC and annealing temperature. Runs privately in your browser. | science | Open tool |
| Probability Calculator | Calculate union, intersection, conditional probability, and complements. Check event consistency and see formulas, steps, percentages, and a Venn diagram. | statistics-probability | Open tool |
| Professional Audio Level Converter — dBu, dBV, Volts & dBFS | Convert professional audio levels between dBu, dBV, volts RMS, millivolts, and calibrated dBFS. Includes sine-wave peak voltage, copy, and CSV export. | studio | Open tool |
| Profit Margin Calculator – Gross, Operating and Net Margin | Calculate gross, operating and net profit margins from revenue and expenses or known profit figures. See profit amounts, formulas and a margin breakdown. | finance | Open tool |
| Project ROI Calculator – Compare Multiple Projects | Compare project ROI, net benefit, annualized ROI, payback, rankings, scenarios, and cost-weighted portfolio ROI with simple or forecast inputs. | finance | Open tool |
| Projectile Motion Calculator: Range, Height and Flight Time | Calculate projectile range, height, flight time, velocity, trajectory, target speed or target angles with steps. Supports SI and Imperial units. | science | Open tool |
| Proportion Calculator: Solve for X with Steps | Solve a missing value or check four values in a/b = c/d. Supports fractions, decimals, signed numbers, and scientific notation with exact steps. | algebra | Open tool |
| Protein Concentration Calculator (Bradford · BCA · A280) | Estimate protein concentration using Bradford, BCA, or direct A280. Supports replicates, blank subtraction, standard curves, and quadratic BCA fitting. | science | Open tool |
| Protein Intake Calculator — Daily Protein by Goal and Activity | Calculate a daily protein range by body weight, goal, activity, age group, and meals per day. See grams per day, per meal, per kg, and per lb. | health | Open tool |
| Protein pI Calculator – Isoelectric Point from Sequence | Calculate theoretical protein or peptide isoelectric point from sequence, compare EMBOSS, Bjellqvist and IPC methods, plot charge vs pH, and analyze multi-FASTA records. | science | Open tool |
| Prüfer Code Encoder and Tree Decoder | Encode a labeled tree as a Prüfer sequence or decode a Prüfer code into its unique tree. See every smallest-leaf step, visualize the result, and export it. | discrete-mathematics | Open tool |
| Purchasing Power Parity (PPP) Calculator by Country | Compare a salary or budget between countries with matched 2024 World Bank private-consumption PPP factors. See the formula, data year, international-dollar value, and limitations. | finance | Open tool |
| Pyramid Calculator: Volume, Surface Area, Height & Slant Height | Solve a regular pyramid from base edge, height, slant height, surface area, or volume. Supports square and triangular pyramids. | geometry | Open tool |
| Pythagorean Triple Generator and Checker | Generate, find, and check Pythagorean triples. List triples by limit, use Euclid's formula, search by a known side or perimeter, and see detailed working. | geometry | Open tool |
| QR Decomposition Calculator with Steps | Calculate the QR decomposition of a square or tall matrix. See Q, R, every Householder reflection, rank, orthogonality, and reconstruction checks. | linear-algebra | Open tool |
| QTc Calculator — Corrected QT Interval by Multiple Formulas | Calculate corrected QT interval (QTc) with Bazett, Fridericia, Framingham and Hodges formulas from QT plus heart rate or RR interval. | health | Open tool |
| Quadratic Formula Calculator and Quadratic Equation Solver — Step-by-Step | Paste a quadratic equation or enter a, b, and c. Get exact and decimal roots, discriminant, graph, and steps by formula, factoring, or completing the square. | algebra | Open tool |
| Quadratic Residue and Legendre Symbol Calculator | Calculate the Legendre symbol (a/p), test quadratic residues modulo an odd prime, and find both modular square roots with exact steps. | number-theory | Open tool |
| Quantum Entanglement Simulator and CHSH Bell Inequality Calculator | Predict or calculate a CHSH Bell-test S value from analyzer angles, measured correlations, or coincidence counts. Explore Bell states, noise, uncertainty, and optional optical-link loss. | science | Open tool |
| Quantum Gate Truth Table Generator & Basis-State Simulator | Generate quantum gate tables, exact amplitudes, probabilities, phases, gate and circuit unitary matrices for ideal 1–3 qubit circuits. | science | Open tool |
| Quantum Tunneling Calculator for a Rectangular Barrier | Calculate exact quantum transmission and reflection through a finite rectangular barrier, compare the WKB approximation, change particle and units, and inspect logarithmic plots. | science | Open tool |
| Quarter Mile Calculator: ET and Trap Speed | Calculate quarter-mile ET and trap speed from horsepower and race weight, estimate HP from time slips, and compare Fox, Hale, and Huntington models. | automotive | Open tool |
| Qubit States and State-Vector Memory Calculator | Calculate 2^n qubit basis amplitudes and dense state-vector or density-matrix RAM. Includes binary units, practical reserve, formulas, and examples. | science | Open tool |
| Race Split Calculator for 5K, 10K, Half Marathon and Marathon | Running split calculator for finish time or pace. Build even or negative splits for 5K, 10K, half marathon, marathon, ultras and custom races. | health | Open tool |
| Rack Unit Calculator | Convert rack units to inches, feet, and centimeters, then plan rack space, rack count, and utilization with mixed device heights, reserve U space, and growth. | infrastructure | Open tool |
| Radical Expression Simplifier with Steps | Simplify square roots, cube roots, and nth-root expressions exactly. Extract perfect powers, combine like radicals, and see every step. | algebra | Open tool |
| RAID Calculator – Capacity, Overhead & Fault Tolerance | Calculate usable RAID capacity, read/write performance, fault tolerance, hot spares, cost per usable TB, and target drive counts for RAID 0, 1, 5, 6, 10, 50, and 60. | infrastructure | Open tool |
| Rain Garden Size Calculator: Area, Runoff Volume & Drain Time | Calculate rain garden bottom area, runoff volume, drain time, footprint, and excavation for roof, driveway, patio, lawn, or mixed catchments. | environment | Open tool |
| Rainwater Collection Calculator — Roof Yield and Tank Size | Calculate rainwater collection in litres or US gallons from a storm, monthly rainfall, or annual rainfall, then estimate cistern or rain barrel storage from demand. | environment | Open tool |
| Raised Bed Soil Calculator: Volume, Bags and Soil Mix | Calculate raised bed soil volume, custom soil-mix quantities, bag counts, bulk amounts, and costs for one or multiple rectangular, circular, or L-shaped beds. | agriculture | Open tool |
| Random Date Generator – Pick Dates Between Two Dates | Pick one or many random calendar dates between two inclusive dates. Filter weekdays, choose predictable formats, and export TXT, CSV, or JSON locally. | random | Open tool |
| Random IP Generator – IPv4, IPv6, Public & Private | Generate bulk random IPv4 and IPv6 addresses locally in your browser. Choose public, private, documentation, CIDR, or custom range modes and export instantly. | random | Open tool |
| Random Letter Generator | Generate one or multiple random letters with filters for A–Z, vowels, consonants, custom alphabets, Greek, Russian, and Spanish. Free, private, and fully client-side. | random | Open tool |
| Random MAC Address Generator | Generate valid fake or dummy MAC addresses for testing. Create local unicast, vendor-prefix, multicast, range-constrained, and bulk MACs in common formats. | random | Open tool |
| Random Number Generator | Generate one or more random integers or decimals between any minimum and maximum. Use unique results, exclusions, presets, lists, CSV, or JSON. | random | Open tool |
| Random Number Set Generator | Generate one or many random number sets, with no repeats, custom ranges, sorting, decimals, and spreadsheet-ready CSV, row, or column output. | random | Open tool |
| Random Picker — Pick a Random Item or Winner from a List | Pick a random item, name, or multiple winners from a list with optional no-repeat, weighted, saved, and reproducible draws—all processed privately in your browser. | random | Open tool |
| Random Playing Card Generator — Draw Cards from a Custom Deck | Draw one or more random playing cards from a standard 52-card deck, multiple decks, decks with jokers, or your own custom card list. Free, private, and client-side. | random | Open tool |
| Random Seating Chart Generator — Assign People to Tables or Seats | Create a free random seating chart for tables or numbered seats. Balance table sizes, use a reproducible seed, then copy, download, or print the chart. | random | Open tool |
| Ratio Calculator — Simplify, Scale and Solve Ratios | Simplify, scale, compare and solve ratios, or divide a total in a two- or three-part ratio. Includes exact fraction input, working steps and optional visuals. | algebra | Open tool |
| Rational Equation Solver with Domain Restrictions | Solve rational equations in x with exact polynomial arithmetic, denominator restrictions, extraneous-root checks, real solutions, and step-by-step work. | algebra | Open tool |
| Rational Expression Simplifier — Factor, Cancel and Find Restrictions | Simplify rational expressions in x with exact polynomial factoring and cancellation. See excluded values, domain restrictions, and step-by-step work. | algebra | Open tool |
| RC Time Constant Calculator — τ, Charging & Discharging Curve | Compute RC time constant τ = R·C and plot charging & discharging curves from an initial voltage. Unit-aware inputs (Ω, kΩ, MΩ; F, mF, µF, nF, pF). 100% client-side & private. | science | Open tool |
| Real GDP Growth Calculator | Calculate real GDP, growth between two real GDP values, or convert nominal GDP growth into real growth using the GDP deflator. Includes annualized and per-capita results. | finance | Open tool |
| Real Return Calculator | Compute real returns from nominal return and inflation, or from start/end values with CPI. Also solve for the nominal return needed to hit a target real return. | finance | Open tool |
| Rearrange PDF Pages Online: Reorder, Rotate and Delete | Visually rearrange, rotate, duplicate, insert, or delete PDF pages in your browser. Free PDF organizer with no upload, account, watermark, or installation. | documents | Open tool |
| Rebar Spacing Calculator: Bar Count, Length and Weight | Calculate rebar count or actual spacing, bar length, weight, stock quantities, splices and cost for two-way slab grids in imperial or metric units. | construction | Open tool |
| Recipe Scaler Calculator: Double, Halve or Resize Any Recipe | Paste a recipe, double or halve it, or resize it by servings. Supports mixed numbers, Unicode fractions, ranges, kitchen-friendly rounding, and private client-side use. | cooking | Open tool |
| Rectangle Calculator | Enter rectangle length and width, or another supported pair, to calculate area, perimeter, diagonal, missing sides, aspect ratio and circle measurements. | geometry | Open tool |
| Rectangular Prism Calculator — Volume, Surface Area and Diagonal | Calculate rectangular prism volume, surface area, space diagonal, face diagonals, base area, and edge length from length, width, and height. | geometry | Open tool |
| Recurrence Relation Calculator and Sequence Generator | Generate terms from a recurrence relation and initial values. Supports a(n-k), n, arithmetic, powers, common functions, tables, copy, and CSV download. | discrete-mathematics | Open tool |
| Recurring Date Calculator and Schedule Generator | Generate daily, weekly, monthly, quarterly, yearly, working-day, and nth-weekday schedules. Adjust exceptions and export repeat dates to CSV or ICS. | time-date | Open tool |
| Recycling and Waste Diversion Impact Calculator | Compare recycling, composting, reuse and other waste routes with landfill using sourced EPA WARM v16 factors. See CO₂e change, landfill diversion and calculation evidence. | environment | Open tool |
| Recycling Contamination Checker and Disposal Guide | Check whether a common household item is ready for recycling, needs preparation, belongs at a special collection point, or should stay out of the recycling bin. | environment | Open tool |
| Redact PDF Online | Redact a PDF online for free. Permanently black out text or image areas with no upload, no signup, and private processing in your browser. | documents | Open tool |
| Redshift Distance Calculator (ΛCDM) | Convert redshift z to luminosity distance (D_L), angular diameter distance (D_A), comoving distance (D_C), lookback time, and distance modulus using flat ΛCDM cosmology. Adjustable H₀ and Ωₘ with Planck 2018, SH0ES, and WMAP9 presets. LaTeX export. Runs in your browser. | science | Open tool |
| Reforestation Carbon Calculator: Estimate CO₂ Sequestration | Estimate annual and cumulative CO₂ sequestration from trees, land area, or an annual removal target. Compare gross and risk-adjusted reforestation scenarios. | environment | Open tool |
| Refrigerant Leak CO2e Calculator | Calculate refrigerant leak CO2e from a known leaked mass or equipment charge and annual leak rate. Includes common refrigerants, sourced GWP100 factors, steps, and CSV export. | environment | Open tool |
| Regular Polygon Calculator: Area, Perimeter, Apothem & Angles | Calculate a regular polygon from its side length, apothem, circumradius, perimeter, area, or perimeter and apothem. Includes formulas, steps, angles, and diagonals. | geometry | Open tool |
| Related Rates Calculator with Steps | Solve common related rates problems for circles, spheres, ladders, tanks, moving objects, and rectangles with formulas, substitutions, units, and steps. | calculus | Open tool |
| Relationship Anniversary Calculator | Calculate how long you’ve been together in years, months, days, weeks, and total days. See your next anniversary, countdown, and relationship milestones. | time-date | Open tool |
| Remove Line Breaks Online | Remove line breaks online, join wrapped text, preserve paragraphs, remove blank lines, and collapse extra spaces. Free and private in your browser. | text | Open tool |
| Rent vs Buy Calculator: Should I Rent or Buy a Home? | Use this rent vs buy calculator to compare mortgage, rent, equity, opportunity cost, inflation, PMI, and selling costs over 1–30 years. | finance | Open tool |
| Rental Property Calculator – Cash Flow, Cap Rate and Cash-on-Cash Return | Estimate rental property cash flow, NOI, cap rate, cash-on-cash return, mortgage payment and DSCR from rent, vacancy, expenses and financing. | finance | Open tool |
| Renters Insurance Calculator: Estimate Monthly Cost and Coverage | Estimate a U.S. renters insurance monthly cost from NAIC state benchmarks, or total your belongings to estimate the personal-property coverage you need. | finance | Open tool |
| Reorder Point Calculator: When to Reorder Inventory | Calculate your inventory reorder point, safety stock, inventory position, and whether to reorder now. Free, private, and no sign-up required. | logistics | Open tool |
| Respiratory Rate Counter — Measure Breaths per Minute | Count breaths with a 30- or 60-second timer, or convert a manual count to breaths per minute. Private, client-side respiratory rate tool. | health | Open tool |
| Resume Builder - Clean Printable CV Generator | Build a clean printable resume or CV in your browser. Add experience, education, skills, and projects, then copy, print to PDF, or download an HTML resume. | documents | Open tool |
| Retaining Wall Block Calculator | Calculate retaining wall blocks, caps, base gravel, drainage stone, fabric, pipe, order quantities, and an itemized cost from your wall measurements. | construction | Open tool |
| Retirement Withdrawal Calculator and 4% Rule Simulator | Retirement withdrawal calculator and 4% rule simulator with Monte Carlo success rates, pension income, fees, sequence-risk stress tests, comparison rates, and a detailed projection table. | finance | Open tool |
| Reusable Bag Impact Calculator: Compare Shopping Bag Footprints | Compare plastic, paper, polypropylene, cotton, and organic cotton shopping bag footprints. Calculate break-even reuses, annual waste, CO2e, and optional cost savings. | environment | Open tool |
| Reusable Cup Calculator: CO₂ Saved and Break-Even Uses | Calculate reusable cup CO₂ savings, disposable cups and lids avoided, waste, washing water, cost, and climate break-even uses for individuals, workplaces, cafes, and events. | environment | Open tool |
| Reverb Time Calculator | Calculate BPM-synced reverb decay times, pre-delay values, and bar lengths for mixing, vocals, drums, and sound design. | studio | Open tool |
| Rhombus Calculator — Area, Perimeter, Diagonals and Angles | Calculate a rhombus’s area, perimeter, side, diagonals, angles, height and inradius from a side and angle, two diagonals, or a side and diagonal. | geometry | Open tool |
| Rice-to-Water Ratio Calculator: Stovetop, Rice Cooker and Instant Pot | Calculate rice-to-water ratios, water, cook time, servings and complete instructions for stovetop, rice cooker and Instant Pot methods. | cooking | Open tool |
| Riemann Sum Calculator | Calculate left, right and midpoint Riemann sums for a function and interval. Compare approximations, inspect sample points, graph rectangles and download results. | calculus | Open tool |
| Road Trip Fuel Stop Planner | Plan road trip fuel stops from trip distance, tank size, fuel economy, starting fuel, and reserve. See maximum leg range, stop count, and stop distances. | automotive | Open tool |
| Rocket Delta-V Calculator (Multi-Stage) | Multi-stage rocket Δv calculator using the Tsiolkovsky equation (Δv = Isp × g₀ × ln(m₀/mf)). Up to 4 stages with correct cascading mass stacking — each lower stage carries the full upper stack at ignition. Live per-stage and total Δv with chart. 100% browser-based, no login. | science | Open tool |
| ROI Calculator (Return on Investment) | Calculate net profit or loss, ROI percentage, return multiple, and optional annualized ROI from investment cost, final value, and additional costs. | finance | Open tool |
| Roof Pitch Calculator: Rise and Run, Degrees, Slope and Rafter Length | Convert rise and run, X/12 pitch, degrees, or percent slope. Calculate roof pitch, angle, multiplier, rafter length, roof area, and roofing squares. | construction | Open tool |
| Roof Shingle Calculator: Bundles, Squares & Cost | Calculate field-shingle bundles, roofing squares, starter and ridge bundles, underlayment rolls, and optional material cost from roof area, footprint, or multiple roof planes. | construction | Open tool |
| Room Mode Calculator — Axial Frequencies & Acoustic Resonances | Calculate axial room modes from room length, width, height, and air temperature. Find acoustic resonances, harmonics, and near-coincident frequencies. | studio | Open tool |
| Rotational Grazing Calculator: Paddock Size and Number | Calculate rotational grazing paddock size, number of paddocks, grazing duration, recovery time, reserve acreage, herd demand, and a printable rotation schedule. | agriculture | Open tool |
| Row Reduction Calculator — RREF and REF with Steps | Reduce a matrix to RREF or REF with every row operation shown. Paste rectangular or augmented matrices, find rank and pivots, then copy or download the steps. | linear-algebra | Open tool |
| RTO/RPO Calculator for Disaster Recovery and Failover Planning | Calculate estimated RTO, estimated RPO, target gaps, downtime cost, and failover readiness for disaster recovery planning. Private, client-side RTO/RPO calculator. | infrastructure | Open tool |
| Rule of 72 Calculator | Use the Rule of 72 to estimate doubling time or required annual return. Compare Rules 72, 70, and 69.3 with exact compounding, fees, and inflation. | finance | Open tool |
| Running Pace Calculator — Calculate Pace, Time, Distance & Speed | Calculate running or walking pace, race finish time, distance and average speed in miles or kilometres. Includes race presets, dual-unit results and splits. | health | Open tool |
| Safety Stock Calculator: Demand, Lead Time and Service Level | Calculate safety stock and reorder point with fixed lead time, variable lead time, or max-versus-average methods. Compare service levels and analyze demand history. | logistics | Open tool |
| Sail Area-to-Displacement Ratio Calculator | Calculate a sailboat's dimensionless sail area-to-displacement ratio (SA/D) from sail area and displacement, or derive working sail area from I, J, P, and E. | marine | Open tool |
| Sailboat Ballast Ratio and Stability Calculator | Calculate sailboat ballast-to-displacement ratio and optionally estimate the ballast-only righting-moment contribution at a selected heel angle, with metric or imperial units. | marine | Open tool |
| Sailing Distance, Speed and Passage Time Calculator | Calculate sailing passage time, distance, or required average speed in knots, nautical miles, miles, and kilometers, with optional local arrival time. | marine | Open tool |
| Salary Inflation Calculator | Salary inflation calculator for pay raises, CPI adjustments, break-even raises, and purchasing-power comparisons. Private, instant, and client-side. | finance | Open tool |
| Salary to Hourly Calculator UK | Hourly to Salary | Convert UK gross annual salary to hourly pay or hourly wage to annual salary using your actual hours, paid weeks, leave and unpaid overtime. | finance | Open tool |
| Sample Size Calculator for Two Independent Means | Plan a two-sample t-test for independent means. Solve for sample size, achieved power, or minimum detectable effect with exact noncentral-t power. | statistics-probability | Open tool |
| SAS Timestamp Converter: Date & Datetime Since 1960 | Convert SAS date values (days since 1960) and SAS datetime values (seconds since 1960) to calendar dates and back. SAS formats, time zones, hex, batch conversion, and exact fractional input. | time-date | Open tool |
| SAT to ACT Score Converter and ACT to SAT Conversion Chart | Convert SAT to ACT or ACT to SAT with exact official 2018 concordance lookups. See every supported score, ACT-to-SAT ranges, examples, and FAQs. | calculators | Open tool |
| Satellite Orbital Period Calculator — Period, Speed and Altitude | Calculate satellite orbital period, speed, or altitude from altitude, orbital radius, semi-major axis, apogee and perigee around Earth, Moon, Mars, Sun, Jupiter, or a custom body. | science | Open tool |
| Savings Goal Calculator | Calculate how much to save monthly, weekly or daily by a deadline, or estimate when a fixed monthly contribution will reach your savings goal. | finance | Open tool |
| Savings vs Investing Calculator: should you save or invest? | Use this Savings vs Investing Calculator to compare cash, investments, and a custom split, including fees, inflation, risk ranges, and goal suitability. | finance | Open tool |
| Savings Withdrawal Calculator | Calculate how long savings will last with monthly withdrawals, or the monthly income a balance can support for a chosen term. Includes interest and annual increases. | finance | Open tool |
| School Days Left and Semester Counter | Calculate school days left until summer, finals, or semester end. Exclude weekends, holidays, breaks, workdays, and closures with a custom seven-day schedule. | time-date | Open tool |
| Scientific Notation Converter | Convert decimal numbers to scientific notation or scientific and E-notation to standard decimal form. Preserves significant figures without floating-point limits. | algebra | Open tool |
| Seed Germination and Seed Rate Calculator | Calculate seed germination, pure live seed (PLS), corrected seeds or bulk seed weight per acre or hectare, and total seed needed for a field, bed, or garden. | agriculture | Open tool |
| Serial Dilution Calculator and Planner | Serial dilution calculator and planner for stock to target, 10-fold dilution ladders, concentration ranges, replicates, dead volume, and bench-ready dilution protocols. | science | Open tool |
| Series Convergence Calculator with Tests and Steps | Test infinite series for absolute, conditional or divergent behavior. See the nth-term, p-series, comparison, ratio, root and alternating-test steps. | calculus | Open tool |
| Server Power Consumption Calculator | Calculate server power consumption, monthly kWh, electricity cost, BTU/hr heat output, rack load, PSU efficiency, redundancy, and PDU/UPS losses. Private browser-based tool. | infrastructure | Open tool |
| Server Rack and Cabinet Airflow Calculator | Calculate server rack cooling CFM, expected temperature rise, or supported heat load. Includes cabinet presets, altitude correction, design allowances, and scenario comparison. | infrastructure | Open tool |
| Server Rack Heat Load and Cooling Calculator | Convert server rack power to heat load, BTU/hr, cooling tons, airflow and floor-area density. Check reserve, sensible capacity and N, N+1 or 2N redundancy. | infrastructure | Open tool |
| Server Rack Weight and Floor Load Calculator | Calculate loaded server rack weight, design weight, footprint pressure in PSF and kPa, distribution-area load, support loads, and floor-rating utilization. | infrastructure | Open tool |
| Server Refresh Cost Calculator & Replacement Budget Planner | Calculate server replacement cost, refresh timing, monthly funding, warranty exposure, consolidation savings, and three- or five-year server TCO. | infrastructure | Open tool |
| Set Operations Calculator | Calculate set union, intersection, differences, symmetric difference, and complements. Enter text or numbers, remove duplicates, copy results, or download CSV. | discrete-mathematics | Open tool |
| Shade Tree Energy Savings Calculator: AC Cost, kWh and Payback | Estimate how much shade trees can save on air conditioning in year one, at maturity, and over their lifetime, including winter tradeoffs, care costs, ranges, and payback. | environment | Open tool |
| Shift Schedule Calculator | Plan rotating shift schedules with day, night, and off patterns. Estimate cycle hours, average weekly workload, and the next shift date privately in your browser. | time-date | Open tool |
| Shortest Path Calculator — Dijkstra’s Algorithm Visualizer | Find the shortest path in a non-negative weighted graph with Dijkstra’s algorithm. Visualize each iteration, distances, predecessors, and relaxations. | discrete-mathematics | Open tool |
| Shower Water, Energy and Cost Calculator | Calculate shower water use, heating energy, water and sewer charges, total cost and CO₂ per shower and for your household over time. | environment | Open tool |
| Shutter Angle Calculator | Convert frame rate and shutter angle into exposure time and shutter speed. Reverse-calculate shutter angle from FPS and shutter speed. Runs in your browser. | studio | Open tool |
| Sign PDF Online – Add a Signature to PDF Documents | Sign a PDF online for free. Draw, type, or upload a signature, place it on any PDF page, and download privately with no file upload or signup. | documents | Open tool |
| Silage Bunker Calculator: Capacity, Tonnage & Sizing | Calculate silage bunker volume, as-fed and dry-matter tons, usable inventory, feed days, face advance, or required bunker dimensions for multiple bunker shapes. | agriculture | Open tool |
| Similar Triangles Calculator — Scale Factor, Sides and Areas | Find a similar-triangle scale factor from corresponding sides, areas, or a known ratio. Calculate missing side lengths, area ratios, and matching areas with steps. | geometry | Open tool |
| Simple Interest Calculator | Calculate simple interest, final amount, principal, annual rate, or time. Includes steps, schedules, 360/365-day options, examples, and formulas. | finance | Open tool |
| Simple Pendulum Calculator – Period, Frequency, Length & Gravity | Solve a simple pendulum for period, frequency, length, or gravity with unit conversions, planetary presets, exact large-angle correction, and calculation steps. | science | Open tool |
| Simple vs Compound Interest Calculator | Compare simple and compound interest using the same principal, nominal annual rate, term, and optional recurring contributions. See balances, working, EAR, and a detailed schedule. | finance | Open tool |
| Simply Supported Beam Calculator — Reactions, SFD & BMD | Calculate support reactions, shear force diagrams and bending moment diagrams for a simply supported beam with point loads and UDLs. Includes formulas, worked example, max shear and max moment. | science | Open tool |
| Singular Value Decomposition Calculator — SVD with Steps | Calculate the thin SVD A = UΣVᵀ for real matrices up to 8×8. See singular values, rank, Jacobi steps, accuracy checks, and downloadable results. | linear-algebra | Open tool |
| SIP Calculator – Calculate Mutual Fund Returns Online | Calculate monthly SIP maturity value, total investment and estimated mutual fund returns. Includes goal SIP, step-up, inflation and scenario comparisons. | finance | Open tool |
| SLA Uptime and Downtime Calculator | Calculate SLA uptime, allowed downtime, required availability, and time- or request-based error budgets. Compare common availability targets and month conventions. | infrastructure | Open tool |
| Sleep Calculator: What Time Should I Go to Bed or Wake Up? | Calculate bedtime, wake-up time, time in bed, and estimated sleep using age-based sleep needs, adjustable sleep latency, and customizable cycle length. | time-date | Open tool |
| Slope Calculator | Find slope from two points, point and slope, rise over run, or a line equation. Get exact fractions, decimals, gradient, intercepts, equations, graph, and worked steps. | geometry | Open tool |
| Slow Cooker to Oven Conversion Calculator and Chart (Crockpot) | Convert Crockpot or slow cooker Low and High times to a covered 325°F oven with an honest time range, quick chart, dish-specific plan, and food-safety checks. | cooking | Open tool |
| Small Business Insurance Cost Calculator: Monthly and Annual Estimate | Estimate monthly and annual U.S. small business insurance costs for a BOP, general liability, property, workers' comp, professional liability, and cyber coverage. No signup. | finance | Open tool |
| Soil Bulk Density Calculator with Porosity | Calculate soil bulk density, core volume and porosity from dry mass and volume, core dimensions, or known bulk and particle density. Includes texture guidance. | agriculture | Open tool |
| Solar Battery Storage Sizing Calculator — kWh & Ah Battery Bank Size | Calculate solar battery storage size in kWh and Ah. Enter daily usage, backup days, DoD, inverter efficiency, battery efficiency, voltage, and module size for home, RV, cabin, or off-grid battery banks. | environment | Open tool |
| Solar Panel Output Calculator: kWh/day, Roof Tilt, Panels Needed & Savings | Estimate solar panel output in kWh/day, monthly and yearly energy, panels needed, roof area, bill savings, export value and payback. Adjust tilt, azimuth, losses, shading and electricity rates. | environment | Open tool |
| Solar Payback Calculator — Time to Break Even | Estimate solar payback period, 25-year savings, ROI, NPV, IRR, and financing cash flow from a quote or rough system estimate. Private, 100% client-side. | environment | Open tool |
| Solar Water Heater Savings & Payback Calculator | Estimate solar water-heating energy savings, annual bill savings, simple payback, break-even year, lifetime cash flow, and NPV. Free and private. | environment | Open tool |
| Sort Lines Alphabetically or Numerically Online | Sort lines alphabetically or numerically online. Alphabetize lists A–Z or Z–A, sort numbers 0–9, use natural sort, remove duplicates, trim spaces, and copy or download the result. | text | Open tool |
| Sound Pressure Level Distance Calculator — Inverse Square Law & Speaker SPL | Calculate sound pressure level at a new distance with the inverse square law, or estimate speaker SPL from sensitivity, amplifier power, and listening distance. | studio | Open tool |
| Sourdough Starter Feeding Calculator | Calculate sourdough starter feed amounts by ratio or target weight, account for starter hydration, and plan local feeding and estimated peak times. | cooking | Open tool |
| Sous Vide Time and Temperature Calculator | Calculate a conservative sous vide pasteurization time from food thickness and water-bath temperature. Supports chilled meat, fish, and poultry in °F, °C, inches, or millimetres. | cooking | Open tool |
| Speaker Impedance Calculator — Series, Parallel & Mixed Wiring | Calculate total speaker impedance for series, parallel, and mixed series-parallel wiring. Check amplifier load, branch current, and ideal power sharing. | studio | Open tool |
| Specific Heat Calculator | Solve heat energy, mass, specific heat capacity, or temperature change using q = mc Delta T. Supports joules, calories, grams, kilograms, and common heat-capacity units. | science | Open tool |
| Speed of Light Distance Calculator | Speed of light distance calculator. Enter any time to see how far light travels in vacuum, or enter distance to find light travel time for the Moon, Sun, AU, and more. | fun | Open tool |
| Speed of Sound in Air vs Temperature Calculator | Calculate the speed of sound in air from temperature in °C, °F, or K. Includes m/s, mph, ft/s, humidity correction, formula, and temperature table. | science | Open tool |
| Speed of Sound in Gases Table and Calculator | Searchable speed of sound in gases table with standard 0 °C and 20 °C comparisons, gas formulas, source notes, and an ideal-gas sound speed calculator. | science | Open tool |
| Speedometer Calibration Calculator | Calculate actual speed after tire-size or axle-ratio changes. Compare metric tire diameters, speedometer error, calibration factor, pulses per mile, and driven gear teeth. | automotive | Open tool |
| Sphere Calculator: Volume, Surface Area, Radius, Diameter & Circumference | Enter radius, diameter, circumference, surface area, or volume to solve every sphere measurement. Includes decimal results, exact π answers, steps, units, and private client-side calculations. | geometry | Open tool |
| Spin the Wheel – Free Random Name Picker & Wheel Spinner | Spin a free random name picker for classrooms, giveaways, prizes, chores and decisions. No sign-up, private on your device, fair and easy to share. | random | Open tool |
| Split Bill Calculator with Tip & Tax – Equal or Itemized | Split a restaurant bill evenly or by item. Add tax, fees, discounts and tip, assign shared dishes, and calculate each person's exact share. | finance | Open tool |
| Split PDF Online – Extract Pages into Separate PDF Files | Split a PDF into separate page files free in your browser. Choose all, odd, even, or custom pages, then download individual PDFs or one ZIP. No uploads. | documents | Open tool |
| Sprayer Calibration & Tank Mix Calculator — GPA, L/ha and Acres per Tank | Calculate actual GPA or L/ha, compare it with a label target, run a nozzle catch test, find acres or hectares per tank, and plan product for full and partial loads. | agriculture | Open tool |
| Square Calculator: Area, Perimeter, Diagonal & Side | Enter a square's side, area, perimeter, diagonal, inradius, or circumradius to calculate every other measurement with exact values and steps. | geometry | Open tool |
| Square Footage Calculator | Calculate square footage with feet-and-inches or metric inputs. Measure irregular rooms and walls, subtract openings, add waste, estimate cost, and round material packages. | construction | Open tool |
| SSL Certificate Expiry Checker and Reminder Calendar | Check a live domain or import a TLS certificate, see its exact expiry and days remaining, then create Google, Outlook, or Apple Calendar reminders. | infrastructure | Open tool |
| Stair Calculator: Rise, Run, Treads & Stringer Length | Calculate stair rise, run, treads, angle, stringer length, layout alternatives, and clearly sourced code checks in Imperial or Metric units. | construction | Open tool |
| Stirling Numbers and Bell Numbers Calculator | Calculate signed and unsigned Stirling numbers of the first kind, Stirling numbers of the second kind, and Bell numbers with exact integer results. | discrete-mathematics | Open tool |
| Stock Return Calculator with Dividends | Calculate historical or manual stock returns with dividends, DRIP, fees, contributions, CAGR or XIRR, and an optional market benchmark. | finance | Open tool |
| Stoichiometry Calculator: Mole Ratios, Limiting Reagent and Yield | Enter a chemical equation and known amount. Automatically balance it, find the limiting reagent, and calculate product mass, excess reagent, or percent yield. | science | Open tool |
| Storage Capacity Calculator and Growth Planner | Calculate storage to provision from ingest or current data, retention, compression, copies, snapshots, filesystem overhead, growth, and free-space reserve. Includes forecasts, scenarios, presets, and RAID array sizing. | infrastructure | Open tool |
| Strong Password Generator | Create unlimited cryptographically secure passwords and memorable passphrases locally in your browser. Free, private, no account, and nothing is sent to a server. | random | Open tool |
| Structured Cabling Length Estimator | Estimate structured cabling length from cable runs, service loops, routing allowance and waste. Plan boxes or reels and screen copper permanent-link length. | infrastructure | Open tool |
| Stucco and Plaster Bag Calculator | Calculate whole stucco, plaster, skim or render bags by coat. Enter walls or rooms, subtract openings, use label coverage, and estimate material, water and cost. | construction | Open tool |
| Student Loan Repayment Calculator | Estimate student loan monthly payments, total interest, payoff date, extra-payment savings, daily interest, and a downloadable amortization schedule. | finance | Open tool |
| Studio Lighting Ratio Calculator — Key, Fill & Contrast in Stops | Calculate studio key-to-fill ratio, combined lighting ratio, and highlight-to-shadow contrast in stops from lux, foot-candle, or relative light readings. | studio | Open tool |
| Studio Monitor Time Alignment Calculator — Distance, Delay & Phase | Calculate studio monitor time alignment from two listening distances. Find which channel to delay, milliseconds, samples, and phase offset. | studio | Open tool |
| Sum of Two Squares Calculator and Representation Finder | Check whether n is a sum of two integer squares and find every unique representation a² + b² = n, with prime-factor theorem steps and exact verification. | number-theory | Open tool |
| Supply Chain Lead Time Calculator | Calculate end-to-end supply chain lead time, delivery dates, latest safe order dates, buffers, business days, uncertainty, and scenario savings. | logistics | Open tool |
| Surface Area Calculator | Calculate total, lateral, curved, and open surface area for prisms, cylinders, cones, pyramids, spheres, and more. See substitutions, exact pi forms, decimals, and conversions. | geometry | Open tool |
| Surface Area of Revolution Calculator | Calculate surface area by rotating y=f(x) or a parametric curve around a line. See the integral, derivatives, graph, error estimate, and CSV data. | calculus | Open tool |
| Suspension Spring Rate Calculator | Calculate suspension spring rate, wheel rate, ride frequency, corner sprung weight, and static deflection from vehicle weight and motion ratio. | automotive | Open tool |
| Switch Port Capacity and Utilization Calculator | Calculate used, free, reserved, unavailable, and needed switch ports by closet; forecast exhaustion; or measure Tx/Rx bandwidth utilization. | infrastructure | Open tool |
| Synthetic Division Calculator with Remainder | Use synthetic division with exact fractions. Enter polynomial coefficients and c for the divisor x − c to get the quotient, remainder, table, and steps. | algebra | Open tool |
| System of Equations Solver — Substitution, Elimination and Graphing | Solve two linear equations in x and y by substitution, elimination, and graphing. Get exact fractions, decimals, checks, and parallel or coincident line detection. | algebra | Open tool |
| System of Linear Equations Solver using Gaussian Elimination | Solve 2–8 linear equations with Gaussian elimination. See row swaps, elimination and back-substitution, classify every solution set, then copy or download the steps. | linear-algebra | Open tool |
| Tangent and Normal Line Calculator | Find tangent and normal line equations for y=f(x) at a point. See the derivative, slopes, point-slope forms, graph, and calculation steps. | calculus | Open tool |
| Taylor and Maclaurin Series Calculator with Steps | Build Taylor and Maclaurin polynomials through order 10. See derivatives, coefficients, point approximations, errors and a graph with step-by-step working. | calculus | Open tool |
| TCP Throughput Calculator | Calculate TCP throughput from receive window size, round-trip time, packet loss, MSS, and link speed. Includes BDP, Reno loss estimate, transfer time, and window scaling. | infrastructure | Open tool |
| TDEE Calculator: Maintenance Calories, BMR, and Macros | Use this TDEE calculator to estimate maintenance calories, BMR, activity needs, goal calories, macros, and optional Katch-McArdle body-fat-based results. | health | Open tool |
| Teleprompter Reading Time Calculator — Script Length, WPM & Video Duration | Paste a teleprompter script or enter its word count to estimate reading time and video duration from WPM, extra time, and an optional target runtime. | studio | Open tool |
| Temperature Converter: Celsius to Fahrenheit, Kelvin & More | Convert Celsius to Fahrenheit, Fahrenheit to Celsius, Kelvin, Rankine, and Réaumur instantly. See the formula, worked result, and common temperature tables. | calculators | Open tool |
| Tetrahedron Calculator — Volume, Surface Area and Height | Calculate a regular tetrahedron’s volume, surface area, height, edge length and radii from any one measurement, with units and calculation steps. | geometry | Open tool |
| Three-Phase PDU Load Balancing Calculator | Calculate three-phase PDU current imbalance, capacity, neutral-current estimate, and the best named load to move. Supports measured, Wye line-neutral, and line-line banks. | infrastructure | Open tool |
| Thunder Distance Calculator | Thunder distance calculator for seconds after lightning, with miles, kilometers, sound travel time, speed of sound, flash timer, and echo mode. Private, client-side. | fun | Open tool |
| Tide Height and Safe Passage Window Calculator | Estimate tide height between three consecutive high and low waters, required tide height, threshold crossings, and a continuous passage window. | marine | Open tool |
| Tile Grout Calculator - How Much Grout Do I Need? | Estimate how much grout to buy from tile size, joint width, grout depth, project area, waste, bag size, and product type. Supports imperial and metric units. | construction | Open tool |
| Time Since or Until a Date Calculator | Find how long ago a past date was, count down to a future date, or compare two dates with calendar and total elapsed time results. | time-date | Open tool |
| Time Zone Converter & Meeting Planner | Convert present, past, or future times between cities and find practical meeting times across multiple locations. Free, private, DST-aware, and browser-based. | time-date | Open tool |
| Time-Weighted Return Calculator (TWR/TWRR) | Calculate cumulative and annualized TWR from cash-flow boundary valuations, dated Modified Dietz cash flows, or a list of known subperiod returns. | finance | Open tool |
| Timecode Calculator — Add, Subtract & Convert Frames | Add and subtract SMPTE timecode or convert timecode to frames and frames to timecode. Supports common frame rates, 29.97 and 59.94 drop-frame. | studio | Open tool |
| Timelapse Calculator: Interval, Frames and Shooting Time | Calculate timelapse interval, frames, shooting time, clip duration, shutter guidance, speed-up and storage for cameras, GoPros, phones and long-term projects. | studio | Open tool |
| Timestamp Converter (UNIX ↔ Date) | Convert Unix timestamps to human-readable dates and back. Handles seconds, milliseconds, microseconds and nanoseconds. Shows UTC, local time, ISO-8601 and any timezone. Batch convert, permalink, and 13 language code examples — private and client-side. | time-date | Open tool |
| Tip Calculator & Bill Splitter | Calculate the tip, tax, total bill, and each person's share. Compare common tip rates, enter an exact tip, or split a bill equally or by each order. | finance | Open tool |
| Tire Pressure Calculator | Estimate tire pressure change with temperature and screen a cold PSI adjustment for a changed per-tire load. Supports PSI, kPa, bar, °F, °C, pounds, and kilograms. | automotive | Open tool |
| Tire Size Calculator – Compare Stock vs New | Use this tire size calculator to compare stock and new tire sizes by diameter, circumference, sidewall height, revs per mile/km, ride height change, and speedometer error. | calculators | Open tool |
| Topological Sort Calculator for Directed Acyclic Graphs | Topologically sort a directed acyclic graph with Kahn's algorithm. Find a valid order, levels, uniqueness, indegrees, and cycles from an edge list. | discrete-mathematics | Open tool |
| Torque & Moment of Inertia Calculator (τ = Iα) | Solve torque, mass moment of inertia, or angular acceleration; calculate force torque with an angle; and find inertia for common rigid-body shapes. | science | Open tool |
| Torque Calculator | Calculate torque, force, lever-arm distance, or angle with worked steps, presets, net torque, and conversions between N·m, lb-ft, in-lb, and more. | science | Open tool |
| Torus Calculator — Volume, Surface Area and Radii | Calculate torus volume, surface area, major and minor radii, inner and outer radii, and diameters. Includes formulas, steps, units, copy, and download. | geometry | Open tool |
| Tower of Hanoi Online — Free Puzzle Game & Auto Solver | Play Tower of Hanoi online for free. Move 3–8 disks, track optimal moves, undo mistakes, save your best score, or watch the auto solver show the minimum-move solution step by step. | games | Open tool |
| Towing Capacity Calculator | Check loaded trailer weight against towing capacity, GCWR, vehicle payload, trailer GVWR and hitch tongue limits. Includes lb/kg units and clear safety margins. | automotive | Open tool |
| Tractor Field Capacity Calculator (Acres per Hour) & Fuel Cost | Calculate tractor acres or hectares per hour, job time, fuel use, and fuel cost per acre with operation presets, overlap controls, and optional PTO power estimates. | agriculture | Open tool |
| Transitive Closure Calculator for Binary Relations | Find the transitive closure of a finite binary relation from ordered pairs or a 0–1 matrix. See added pairs, the closure matrix, and exportable results. | discrete-mathematics | Open tool |
| Trapezoid Calculator: Area, Perimeter, Height and Sides | Calculate trapezoid area, perimeter, height, missing bases, sides, diagonals and angles with clear modes, validation and step-by-step working. | geometry | Open tool |
| Travel Insurance Cost Calculator: Estimate Your Trip Premium | Estimate UK single-trip travel insurance cost in GBP using trip dates, destinations, individual ages, policy type and coverage level. See a range, per-person cost and full methodology. | finance | Open tool |
| Triangle Calculator — Solve Any Triangle | Solve a triangle with guided SSS, SAS, ASA/AAS, SSA, right-triangle, and area modes. See checked inputs, worked steps, diagrams, and derived properties. | geometry | Open tool |
| Triangle Solver Calculator: Law of Sines & Cosines | Triangle calculator for SSS, SAS, ASA/AAS, SSA, and auto-detect cases. Solve sides, angles, area, perimeter, radii, and steps with pi-radian input support. | geometry | Open tool |
| Triangular Prism Calculator — Volume, Surface Area and Length | Calculate a right triangular prism’s volume, surface area, or length from three base side lengths. Includes units, formulas, validation, copy, and CSV. | geometry | Open tool |
| Trigonometry Calculator | Calculate sin, cos, tan, sec, csc, cot, inverse trig, pi radian expressions, exact values, and right-triangle SOHCAHTOA results in degrees or radians. | calculators | Open tool |
| Truck & Container Load Utilization Calculator | Calculate truck, container, pallet and cargo load utilization by weight, volume, CBM, cubic feet and estimated space fit. Fast, private logistics tool. | logistics | Open tool |
| Truck Cost Per Mile Calculator | Calculate trucking cost per mile, cost per loaded mile, cost per kilometer, deadhead percentage, break-even rate, and profit per mile for fleets and owner-operators. | logistics | Open tool |
| Truth Table Generator for Propositional Logic | Generate complete propositional logic truth tables with intermediate steps. Supports NOT, AND, OR, XOR, implication, biconditional, constants, copy, and CSV download. | discrete-mathematics | Open tool |
| Turbo Boost and Horsepower Calculator | Calculate turbo pressure ratio, ideal horsepower, estimated power gain, and boosted horsepower from baseline power, gauge boost, ambient pressure, and a realization factor. | automotive | Open tool |
| Turkey Cooking Time Calculator | Calculate turkey roasting time by weight, oven temperature, stuffing, and servings. Includes USDA-based 325°F times, start time, rest time, and safe temperature checks. | cooking | Open tool |
| UK Retirement Calculator | Use this UK retirement calculator to estimate the pension pot you need, sustainable retirement income, savings shortfall and monthly contribution required. | finance | Open tool |
| UK VAT Calculator: Add or Remove VAT | Free UK VAT calculator to add or remove 20%, 5%, 0% or custom VAT. See net, VAT, gross and live workings, with optional international rates. | finance | Open tool |
| ULID Generator | Generate secure, sortable ULIDs in your browser. Create monotonic batches, copy or download them, and validate or decode ULID timestamps privately. | random | Open tool |
| Unit Converter | Unit converter for length, weight, temperature, area, volume, speed, pressure, energy, data, fuel economy, and more. Fast, accurate, private. | calculators | Open tool |
| Unit Price Calculator | Compare unit prices for groceries, supplies, and bulk packs. Calculate cost per ounce, gram, pound, kilogram, fluid ounce, liter, or item. Private, client-side. | calculators | Open tool |
| Universe Age, Lookback Time and Distance Calculator | Find the age of the universe at a redshift, lookback time, and cosmological distances. Includes Planck 2018 presets, reverse calculations, formulas, and an accessible chart. | science | Open tool |
| Unix Hex Timestamp Converter — Hex/Decimal Seconds or Milliseconds ↔ Date | Paste a Unix timestamp in hex (0x6502FACE) or decimal — get UTC date, ISO-8601, seconds and milliseconds instantly. Auto-detects unit, batch convert, compare mode, 9-language code snippets. 100% client-side, no login. | time-date | Open tool |
| Unlock PDF Online – Remove a Known PDF Password | Unlock a PDF with its known password and download a password-free copy. Private browser processing preserves PDF content with no document upload. | documents | Open tool |
| UPS Runtime Calculator | Calculate UPS runtime from battery voltage, Ah, load watts, efficiency, and derating. Estimate backup time, required battery capacity, and UPS kVA size with formulas and examples. | infrastructure | Open tool |
| Urban Heat Island Calculator — Urban Heat Reduction Tool | Estimate baseline urban heat island intensity, then compare cooling from trees, shade, cool roofs, cool pavement, and green roofs. Includes presets, material defaults, and editable assumptions. | environment | Open tool |
| URL Encoder & Decoder Online | Encode or decode URLs and query strings (percent-encode) with encodeURIComponent / decodeURIComponent — fast, accurate, and 100% client-side for privacy. | web | Open tool |
| USDA Soil Texture Triangle Calculator – Sand, Silt & Clay | Plot sand, silt, and clay percentages on the USDA soil texture triangle, identify the exact 12-class texture, normalize rounded values, or convert a jar test. | agriculture | Open tool |
| UUID v1 Generator | Generate free, private, RFC 9562-compliant UUID v1 identifiers in your browser. Create one time-based UUID or export batches of up to 1,000. | random | Open tool |
| UUID v3 Generator | Generate deterministic, RFC 9562 compliant UUID v3 values from a namespace and exact name bytes. Includes the official test vector, batch CSV export, and code examples. | random | Open tool |
| UUID v4 Generator | Generate one or up to 10,000 cryptographically random UUID v4 values locally. Format, copy, download, and validate UUIDs online for free. | random | Open tool |
| UUID v5 Generator | Generate deterministic UUID v5 identifiers from an exact UTF-8 name and DNS, URL, OID, X.500, or custom namespace, following RFC 9562. | random | Open tool |
| UUID v7 Generator | Generate private, RFC 9562 UUID v7 identifiers in your browser. Create time-ordered UUIDs in batches, copy or download them, and decode timestamps. | random | Open tool |
| Variance Calculator | Calculate population and sample variance, standard deviation, mean, deviations, and squared deviations from a number list with clear step-by-step results. | statistics-probability | Open tool |
| Vector Components Calculator — Find X, Y and Z Components | Calculate x, y and z vector components from magnitude and direction, or recover magnitude, azimuth and elevation from components. Includes steps and projection. | linear-algebra | Open tool |
| Vector Projection Calculator (2D & 3D) | Project one 2D or 3D vector onto another with step-by-step work. Includes scalar and vector projection, rejection, dot product, angle, magnitudes, cross product, and area. | linear-algebra | Open tool |
| Vehicle Maintenance Schedule Generator | Build a vehicle-specific maintenance schedule from mileage and time intervals. Prioritize overdue, due-soon, and upcoming service without uploading your data. | automotive | Open tool |
| Vehicle Payload Calculator | Calculate vehicle payload used, remaining capacity, and estimated loaded weight from GVWR or a door-label payload limit. Includes passengers, cargo, equipment, and trailer tongue weight. | automotive | Open tool |
| Vehicle Power-to-Weight Ratio Calculator | Calculate vehicle power-to-weight ratio in hp/ton, hp/1,000 lb, W/kg, lb/hp, and estimate an ideal acceleration time for a chosen speed interval. | automotive | Open tool |
| Vehicle Stopping Distance Calculator | Calculate stopping distance from speed, reaction time, braking deceleration or friction, and road grade. See reaction and braking distances in feet and meters. | automotive | Open tool |
| VHF Radio Horizon and Communication Range Calculator | Estimate marine VHF radio horizon and two-antenna communication range from antenna heights, compare standard and geometric models, and check a planned path. | marine | Open tool |
| Video File Size & Footage Storage Calculator | Calculate video file size, GB/TB storage, recording time, bitrate, card capacity, resolution, frame rate, and codec estimates for ProRes, H.264, H.265, DNxHR, BRAW, REDCODE, DCP, and uncompressed footage. | studio | Open tool |
| Video Speed Ramp Calculator — Playback Speed, Frames & Clip Duration | Calculate speed-ramp playback duration, effective speed, source and timeline frames, frame rounding, and linear or eased ramp curves. | studio | Open tool |
| VLAN Planner & IP Address Plan Generator | Free browser-based VLAN planner for IPv4 and IPv6. Build FLSM or host-driven VLSM plans with gateways, DHCP pools, conflict checks, templates, CSV/JSON export, and local save. | infrastructure | Open tool |
| VM Consolidation Ratio & Host Sizing Calculator | Measure VMs per host and vCPU:pCore, or size VM hosts using CPU demand, RAM, storage, growth, and N+1 availability. | infrastructure | Open tool |
| Voice-Over Length Calculator — Word Count, Speaking Rate & Recording Time | Calculate voice-over length from a script or word count and WPM. Estimate raw recording and studio session time using takes, pickups, and setup time. | studio | Open tool |
| Voltage Divider Calculator | Calculate a resistor or potential divider: solve Vout, Vin, R1, or R2, compare loaded output, analyze tolerance, and find standard resistor pairs. | calculators | Open tool |
| Volume of Revolution Calculator | Calculate volumes of revolution with disk, washer, or cylindrical shell methods. Enter functions, bounds, and an axis to see the integral, graph, error estimate, and CSV data. | calculus | Open tool |
| VO₂ Max Estimator | Estimate VO2 max from a Cooper 12-minute run, Rockport one-mile walk, or maximum-to-resting heart-rate ratio. Free, private, client-side calculator. | health | Open tool |
| Waist-to-Hip Ratio Calculator | Calculate waist-to-hip ratio from inches or centimetres and compare it with WHO adult screening cutoffs. Includes measurement guidance and privacy. | health | Open tool |
| Wall Framing Calculator | Calculate wall studs, plates, door and window framing, cut lengths, stock quantities, waste, and optional cost for 2x4 or 2x6 walls in imperial or metric units. | construction | Open tool |
| Wallpaper Calculator: How Many Rolls Do I Need? (Pattern Repeat) | Calculate wallpaper rolls for one wall or a whole room, including trim, openings, straight or half-drop pattern repeat, spare rolls and cost. | construction | Open tool |
| WAN, RTT & Fiber Latency Budget Calculator | Calculate WAN RTT, fiber propagation delay, equipment delay, jitter, TCP impact, and SLA margin from distance in miles or kilometers. Includes quick and advanced modes. | infrastructure | Open tool |
| Warehouse Space Calculator: How Much Space Do You Need? | Estimate total warehouse square footage or pallet capacity from pallets, racking, aisles, operational areas, clear height, and growth reserve. | logistics | Open tool |
| Warshall Algorithm Reachability Matrix Calculator | Calculate a directed graph reachability matrix with Warshall's algorithm. Explore every intermediate matrix step, reachable pairs, and transitive closure. | discrete-mathematics | Open tool |
| Water Intake Calculator: How Much Water Should I Drink? | How much water should you drink? Estimate a daily range by weight, activity, climate and life stage in litres, ounces, cups, glasses and bottles. | health | Open tool |
| Watts / Volts / Amps / Ohms DC Power Calculator | DC watts, volts, amps, and ohms calculator. Solve voltage, current, resistance, or power from any two values with Ohm’s law formulas and worked steps. | calculators | Open tool |
| Wavelength and Frequency Calculator | Convert frequency to wavelength, wavelength to frequency, or solve for wave speed using v = fλ. Includes wave presets, spectrum classification, steps, and conversions. | calculators | Open tool |
| WCAG Color Contrast Checker - AA/AAA Text and UI | WCAG color contrast checker for foreground and background colors, AA and AAA text, large text, icons, and UI components. Supports Hex, RGB, HSL, and CSS names. | web | Open tool |
| Weight on Other Planets Calculator | Enter your Earth weight in lb, kg, or Newtons and see scale weight on the Moon, Mars, Jupiter, and other worlds. Includes factors, examples, and sources. | fun | Open tool |
| What Browser Am I Using? Check Browser Version and Device Info | What browser am I using? Instantly check your browser version, operating system, device, user agent, screen size, and optional public IP. | web | Open tool |
| What Day of the Year Is It Today? | See today's day of year, days left, ISO ordinal date, and leap-year status. Convert dates, day numbers, and Julian-style YYDDD or YYYYDDD codes instantly. | time-date | Open tool |
| Wheel Offset Calculator | Compare current and new wheel width, offset, spacers, inner clearance, outer poke, track width, and approximate backspacing. Free private browser calculator. | automotive | Open tool |
| Wind Turbine Power Output Calculator | Calculate wind turbine power in W, kW or MW and annual kWh using rated capacity factor or a Rayleigh/Weibull distribution and power curve. | environment | Open tool |
| Window U-Value Calculator: Whole-Window Uw, U-Factor & R-Value | Calculate preliminary whole-window Uw from glazing, frame and spacer values, or convert metric and imperial U-values and R-values with a transparent breakdown. | construction | Open tool |
| Wood Stove and Fireplace Emissions Calculator | Estimate annual particle emissions from a wood stove or fireplace using an appliance g/h rating or EPA AP-42 dry-wood factors. Includes moisture, units, steps, and CSV export. | environment | Open tool |
| Word to PDF Converter – Convert DOCX Files Online | Convert a DOCX Word file to PDF in your browser. Preview the document, copy its text, and save a searchable PDF privately with no upload or account. | documents | Open tool |
| Work, Power and Energy Calculator | Calculate work, power, lifting energy, kinetic-energy change, and efficiency. Solve for any unknown with unit conversion, worked steps, and examples. | science | Open tool |
| XML Formatter, Validator & Minifier Online | Format, validate, and minify XML online with clear parsing errors, safe mixed-content handling, local file input, copy, and download. Your XML stays in your browser. | web | Open tool |
| Yeast Conversion Calculator – Active Dry, Instant & Fresh Yeast | Convert yeast between active dry, instant, and fresh yeast by grams, ounces, teaspoons, or packets. Choose practical home-baking or professional weight ratios. | cooking | Open tool |
| Z-Score and Standard Deviation Calculator | Calculate z-scores from x, mean, and standard deviation, reverse z to x, analyze datasets, or compute sample mean z-scores with percentiles and probabilities. | statistics-probability | Open tool |
| Zalgo Text Generator - Copy and Paste Glitch/Cursed Text | Free online Zalgo text generator for copy-paste glitch, cursed, and creepy Unicode text. Works in your browser with presets, cleaner, and platform-safe controls. | text | Open tool |
| Zero-Point Energy Calculator: Vibrational ZPE and Vacuum Energy | Calculate molecular zero-point vibrational energy from wavenumber, frequency, or wavelength, or estimate vacuum energy density in a volume with clear steps and caveats. | science | Open tool |
| ⌨️ Keyboard Mileage Calculator — How Far Do Your Fingers Travel Typing? | Calculate keyboard mileage from pasted text, word count, or typing time. Compare QWERTY, Dvorak, Colemak, and AZERTY finger travel privately in your browser. | fun | Open tool |
| 🎈 Helium Balloon Calculator – How Many to Lift a Person, Dog, or House? | Helium balloon calculator for fun physics: estimate how many balloons it would take to lift a person, dog, car, house, or object. Supports kg/lb and custom balloon sizes. | fun | Open tool |
| 🐌 How Long Would a Snail Take? Snail Travel Time Calculator | Calculate how long a snail would take to travel any distance, then optionally compare its arrival with a postal delivery range. Includes units, assumptions, formulas, and examples. | fun | Open tool |
| 👣 Footsteps Around the World Calculator — How Many Steps to Circle Earth? | Calculate how many footsteps it takes to circle Earth from your step length. Compare equatorial, meridian, and custom routes, plus days and years. | fun | Open tool |
| 🔋 Human Battery Calculator — How Much Energy Does Your Body Use? | Convert your body's daily energy use into watts, kilowatt-hours, phone charges and AA batteries. Use known calories or estimate from body details. | fun | Open tool |
| 😴 Nap Calculator: Find Your Best Nap Length and Wake-Up Time | Use this nap calculator to compare 10, 20, and 90-minute naps, find an estimated wake-up time, protect bedtime, and start a browser countdown. | fun | Open tool |
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