Every calculator you need, in one place
110 calculators that answer as you type — no sign-up, no ads in the way of the answer, and nothing you enter ever leaves your device.
No calculator matches that. Try a broader word.
Money & business
Loans, margins, interest, tax and the ratios that decide whether a business is working.
EBITDA CalculatorEarnings before interest, tax, depreciation and amortisation — plus margin.Loan Payment CalculatorMonthly payment, total interest and the full amortisation for any fixed-rate loan.Mortgage CalculatorMonthly payment including tax, insurance and PMI — the number you actually pay.Car Loan CalculatorMonthly payment on a vehicle after deposit, trade-in and sales tax.Compound Interest CalculatorWhat a balance grows to with regular contributions and compounding.Simple Interest CalculatorInterest charged only on the original amount, never on accrued interest.ROI CalculatorReturn on investment, as a percentage and annualised.CAGR CalculatorCompound annual growth rate — the smooth rate that connects two values.NPV & IRR CalculatorNet present value and internal rate of return for a stream of cash flows.Break-Even CalculatorHow many units you must sell before you stop losing money.Profit Margin CalculatorGross, operating and net margin from revenue and costs.Markup & Margin CalculatorConvert between markup and margin — they are not the same number.Income Tax CalculatorUS federal income tax, effective rate and take-home pay.Salary CalculatorConvert between hourly, weekly, monthly and annual pay.Savings Goal CalculatorWhat you need to put aside each month to reach a target.Credit Card Payoff CalculatorHow long a balance takes to clear, and what the interest costs.Inflation CalculatorWhat an amount is worth after inflation, in either direction.Sales Tax CalculatorAdd tax to a net price, or strip it out of a gross one.VAT CalculatorAdd or remove value added tax at any rate.Tip CalculatorTip and total, split any number of ways.Discount CalculatorFinal price after one or two discounts, and what you save.Depreciation CalculatorStraight line, declining balance and sum-of-years depreciation.
Electronics
Ohm's law, dividers, filters and the sums you do before you reach for the soldering iron.
Ohm's Law CalculatorGive any two of voltage, current, resistance or power — get the other two.Resistor Colour Code CalculatorRead a resistor from its bands, in 4, 5 or 6-band form.Voltage Divider CalculatorOutput voltage, current and power for a two-resistor divider.LED Resistor CalculatorThe series resistor an LED needs, with the nearest standard value.Series & Parallel Resistance CalculatorTotal resistance of any number of resistors, in series or parallel.RC Filter & Time Constant CalculatorCutoff frequency, time constant and rise time for an RC pair.Voltage Drop CalculatorVoltage lost in a copper run, and whether the gauge is adequate.Battery Life CalculatorHow long a battery lasts at a given load, with a realistic derating.Wire Size CalculatorThe smallest wire that carries the current and stays inside the voltage drop limit.Three-Phase Power CalculatorkW, kVA, kVAR and line current, with the √3 in the right place.Transformer CalculatorTurns ratio, winding currents and core size from the voltages and rating.555 Timer CalculatorFrequency, duty cycle and pulse width for astable and monostable 555 circuits.PCB Trace Width CalculatorTrace width for a given current and temperature rise, to IPC-2221.LC Resonance & Reactance CalculatorResonant frequency, reactance, impedance and Q for an LC circuit.Power Factor Correction CalculatorThe capacitor bank needed to raise power factor, and what it saves.Op-Amp Gain CalculatorGain, output voltage and bandwidth for the standard op-amp configurations.Decibel CalculatorConvert between dB, dBm, watts and voltage ratios — with the factor of 10 or 20.
Computing & data
Subnets, bases, bandwidth, colour and entropy.
Image ConvertertoolPNG, JPEG and WebP, with resizing — entirely in your browser.CSV to JSON ConvertertoolConvert between CSV and JSON, both directions, in your browser.QR Code GeneratortoolMake a QR code for a link, wifi network or contact — encoded in your browser, never uploaded.Hash GeneratortoolMD5, SHA-1, SHA-256 and SHA-512 for text or a file — computed in your browser.Password GeneratortoolStrong random passwords and passphrases, generated in your browser with real entropy.JSON Formatter & ValidatortoolFormat, minify and validate JSON — with the error pointed at, not just reported.Base64 Encoder & DecodertoolText or files to Base64 and back, including the URL-safe variant and data URIs.JWT DecodertoolRead the header and claims inside a JSON Web Token, with the timestamps in plain English.UUID GeneratortoolVersion 4 and version 7 UUIDs in bulk, plus a decoder for one you already have.Unix Timestamp ConvertertoolUnix time to a readable date and back, in seconds or milliseconds, UTC or local.Image CompressortoolCompress a photo to a target file size — 100 KB, 500 KB, whatever the form demands.Word & Character CountertoolWords, characters, sentences and reading time — counted as you type, never uploaded.Case ConvertertoolSentence case, Title Case, camelCase, snake_case and the rest — in one click.Diff CheckertoolCompare two texts and see exactly what changed — line by line, word by word.Lorem Ipsum GeneratortoolPlaceholder text by paragraphs, sentences or words — classic Latin or plain English.Subnet CalculatorNetwork, broadcast, host range and mask for any IPv4 CIDR block.Number Base ConverterConvert between decimal, binary, hexadecimal and octal.Download Time CalculatorHow long a transfer takes, and the units people keep confusing.Aspect Ratio CalculatorResize without distortion — give three numbers, get the fourth.Colour ConverterHEX, RGB, HSL and the contrast ratio against black and white.Password Entropy CalculatorHow much real randomness a password has, and how long it survives.Uptime & SLA CalculatorAllowed downtime for any number of nines, and the availability a given outage leaves you.RAID Capacity CalculatorUsable capacity, fault tolerance and write penalty for every common RAID level.Video Bitrate & File Size CalculatorFile size, bitrate or duration — plus what the resolution actually needs.
Engineering & build
Gears, torque, concrete, roofs and the quantities you have to order before you start.
Spur Gear GeneratortoolInvolute spur gears from module and tooth count — download SVG or DXF.Finger Joint Box GeneratortoolLaser-cut boxes with finger joints — enter three dimensions, download the cut file.Bolt Circle GeneratortoolHole positions on a pitch circle, with coordinates and a cut file.Gear Ratio CalculatorRatio, output speed and torque multiplication for a gear pair or train.Torque CalculatorTorque from force and radius, converted between every common unit.Pulley & Belt CalculatorDriven speed, ratio and belt length for a two-pulley drive.Kinetic & Potential Energy CalculatorEnergy and momentum of a moving or raised mass.Projectile Motion CalculatorRange, peak height and flight time for a launch angle and speed.Concrete CalculatorVolume of concrete for a slab, footing or column, and bags needed.Roof Pitch CalculatorPitch, angle, rafter length and the area multiplier.Paint CalculatorHow much paint a room needs, after doors, windows and coats.Board Foot CalculatorBoard feet and cost for rough lumber.Tile & Flooring CalculatorTiles, boxes and adhesive for a floor or wall.Electricity Cost CalculatorWhat an appliance costs to run, per day, month and year.BTU & Air Conditioner Size CalculatorCooling capacity a room needs, adjusted for the things that matter.Molarity & Dilution CalculatorConcentration, mass needed, and the dilution equation.Ideal Gas Law CalculatorSolve PV = nRT for whichever term you are missing.Tap Drill & Thread Size CalculatorTap drill size, clearance hole and thread engagement for metric and unified threads.Cutting Speed, RPM & Feed Rate CalculatorSpindle speed and feed from surface speed and chip load — milling, turning, drilling.Sheet Metal Bend Allowance CalculatorBend allowance, bend deduction and flat pattern length from the K-factor.Bolt Torque CalculatorTightening torque from size, grade and lubrication — with the preload it produces.Beam Deflection CalculatorMaximum deflection, moment and bending stress for the standard load cases.Section Modulus & Moment of Inertia CalculatorArea, I, section modulus and weight per metre for the common structural shapes.Stress, Strain & Elongation CalculatorAxial stress, strain, extension and safety factor from load and section.Belt Length & Pulley CalculatorBelt length, wrap angle and centre distance for open and crossed drives.Compression Spring CalculatorSpring rate, shear stress and solid height from wire size and coil geometry.Hydraulic Cylinder Force CalculatorPush and pull force, speed and flow demand from bore, rod and pressure.Pipe Flow & Pressure Drop CalculatorVelocity, Reynolds number and friction pressure loss in a round pipe.Pump Power CalculatorHydraulic power, shaft power, motor size and running cost from flow and head.Thermal Expansion CalculatorLength change with temperature, and the stress if the part cannot move.Bearing Life CalculatorL10 life in revolutions and hours from dynamic capacity, load and speed.Stair CalculatorRiser height, tread depth, stringer length and the code checks, from total rise.Rebar CalculatorBar count, total length, weight and laps for a slab or footing mat.Tank Volume CalculatorTotal and filled volume for cylindrical, rectangular and spherical tanks.Drywall CalculatorSheets, screws, tape and compound for a room, minus the openings.Gravel, Soil & Mulch CalculatorVolume, weight and bag count for any loose material spread to a depth.Wall Framing CalculatorStuds, plates, headers and noggins for a timber-framed wall.
Health & body
Body composition, energy needs and the dates that matter.
BMI CalculatorBody mass index, with the category and healthy weight range.BMR & TDEE CalculatorResting metabolic rate and daily calorie needs by activity level.Body Fat CalculatorBody fat percentage using the US Navy circumference method.Ideal Weight CalculatorFour established formulas, plus the healthy BMI range.Calorie Needs CalculatorDaily calories and macronutrient split for a weight goal.Water Intake CalculatorDaily fluid target adjusted for body weight, activity and climate.Due Date CalculatorEstimated due date, current stage and trimester dates.Ovulation CalculatorFertile window and ovulation date from your cycle.
Maths
The workings you used to do on paper, done exactly.
Graphing CalculatortoolPlot functions, zoom and trace — with the maths parsed, not evaluated.Percentage CalculatorEvery percentage question, answered at once.Fraction CalculatorAdd, subtract, multiply and divide fractions, simplified.Ratio CalculatorSimplify ratios, scale them, and solve for a missing term.Mean, Median & Mode CalculatorEvery summary statistic for a list of numbers.Standard Deviation CalculatorPopulation and sample standard deviation, variance and standard error.Quadratic Equation SolverRoots, vertex and discriminant for ax² + bx + c = 0.Triangle CalculatorMissing side, area, perimeter and angles of a right triangle.Circle CalculatorArea, circumference, diameter and radius from any one of them.GCD & LCM CalculatorGreatest common divisor and lowest common multiple, with factors.Scientific Notation ConverterConvert between decimal, scientific and engineering notation.
Everyday
Dates, units, journeys, grades and the small sums of ordinary life.
Age CalculatorExact age in years, months and days — plus every other unit.Date Difference CalculatorTime between two dates, in every unit, with or without weekends.Date Add & Subtract CalculatorAdd or subtract days, weeks, months or years from a date.Time Duration CalculatorHours and minutes between two times, with breaks deducted.Unit ConverterLength, weight, temperature, volume, area and speed.Fuel Cost CalculatorWhat a journey costs in fuel, and per person when shared.Speed, Distance & Time CalculatorSolve for any one of the three, plus pace.GPA CalculatorWeighted grade point average on a 4.0 scale.Random Number GeneratorRandom integers in a range, with or without duplicates.Sleep CalculatorBedtimes and wake times aligned to 90-minute sleep cycles.