Calculators
Math, money, electrical and everyday calculators with worked steps. 125 tools, all free and instant.
Math
Percentages, averages, statistics, algebra.
Adding fractionsAdd two fractions and see the common denominator, the addition and the simplified answer — plus the decimal, percentage and mixed-number forms.AdditionAdd two numbers or a whole list of them, with the working shown. Handles decimals, negatives and very large values without losing precision on screen.AntilogReverse a logarithm: enter the exponent and the base to get the original number back, with the substitution shown.ArccosFind the angle whose cosine is a given value, returned in degrees or radians. Accepts any value from −1 to 1.ArcsinFind the angle whose sine is a given value, returned in degrees or radians. Accepts any value from −1 to 1.ArctanFind the angle whose tangent is a given value, returned in degrees or radians — the quickest way to turn a slope into an angle.AveragePaste any list of numbers to get the mean, median, mode, range, sum and count instantly — commas, spaces or new lines all work.Complex numbersAdd, subtract, multiply and divide complex numbers, with the modulus, argument and polar form of the result worked out alongside.ConvolutionConvolve two discrete sequences and see the full output, with the first few terms expanded so you can follow how each one is assembled.CosineCalculate the cosine of any angle in degrees or radians, with the radian conversion and the matching sine and tangent alongside.Dividing fractionsDivide one fraction by another using the reciprocal method, with each step shown and the answer simplified to its lowest terms.DivisionDivide one number by another and see the exact quotient, the whole part, the remainder and the result as a simplified fraction.Exponential growthProject a value forward at a constant growth rate and see the final amount, the multiplier and the doubling time.ExponentsRaise any base to any power, including negative and fractional exponents, and see the result in plain and scientific notation.FactorialCalculate n! exactly for any whole number up to 2000, using big-integer arithmetic so every digit of the answer is correct.FractionsAdd, subtract, multiply and divide fractions. Get the simplified result, the mixed number and the decimal, with every step shown.GCFFind the greatest common factor of two or more numbers, with prime factorisations shown so you can see exactly where the answer comes from.Hex calculatorDo arithmetic and bitwise operations directly in hexadecimal, with every result shown in hex, decimal, binary and octal at the same time.LCMFind the least common multiple of two or more numbers — the smallest value they all divide into — with prime factorisations shown.LogarithmCalculate a logarithm to any base, with the change-of-base working shown and log₁₀, ln and log₂ of the same number side by side.MultiplicationMultiply two numbers or a list of them. Shows the product in plain and scientific notation, which matters once the result runs long.Multiplying fractionsMultiply two fractions — numerators across the top, denominators across the bottom — then see the result simplified to its lowest terms.Natural logCalculate the natural logarithm of any positive number — the logarithm to base e — alongside its base-10 and base-2 equivalents.Nth rootCalculate any root of any number — square, cube, fourth or a fractional degree — with the result checked by raising it back to that power.Percent errorCompare a measured value with the accepted one and get the percent error, the absolute error and the signed error for lab reports.PercentageWork out percentages four ways: X% of Y, X is what % of Y, X is Y% of what, and percentage increase or decrease — with the working shown.Percentage changeFind the percentage change between two numbers, with the direction, the absolute difference and the working shown step by step.Percentage increaseWork out how much a value has grown in percentage terms — for prices, salaries, traffic or any pair of before-and-after numbers.PythagoreanSolve a right triangle from any two sides — find the hypotenuse or a missing leg, plus the area, perimeter and angles.QuadraticSolve ax² + bx + c = 0 for real or complex roots. Shows the discriminant, the vertex, and the full quadratic-formula working.Random numbersGenerate cryptographically secure random numbers in any range. Choose how many, allow or forbid duplicates, sort and copy in one click.RatioSimplify a ratio to its lowest terms and solve proportions — enter A : B and a value for C to find the matching D.RemainderDivide two numbers and get the quotient and the remainder separately, plus the modulo result for negative dividends.ScientificFull scientific calculator with trigonometry, logs, powers, roots, memory keys and a running history tape. Works with your keyboard.Scientific notation calcWork out scientific notation step by step: turn a plain number into a × 10ⁿ or expand it back, with engineering and E notation shown for each result.Simple calculatorA plain four-function calculator with a keypad, percentage and sign keys, and a running history tape of everything you have worked out.Simplifying fractionsReduce any fraction to its lowest terms, with the greatest common factor shown, plus the decimal, percentage and mixed-number equivalents.SineCalculate the sine of any angle in degrees or radians, with the radian conversion and the matching cosine and tangent shown.Square rootFind the square root of any positive number to ten significant figures, with the cube root and a verification step shown alongside.Std deviationCalculate population and sample standard deviation, variance, mean and the full step-by-step working from any list of numbers.Subtracting fractionsSubtract one fraction from another with the common denominator, the subtraction and the simplification all written out step by step.SubtractionSubtract one number from another, or work through a list from left to right, with each step of the calculation written out.TangentCalculate the tangent of any angle in degrees or radians, with the radian conversion and the sine and cosine it is built from.TrigonometryCalculate sin, cos, tan and their inverses in degrees or radians, with all three ratios shown at once and the conversion written out.VarianceCalculate sample or population variance and standard deviation from a list of numbers, with the sum of squares shown.Weighted averageAverage a set of values where some count more than others — add as many value-and-weight pairs as you need and see both averages.
Financial
Loans, interest, discounts and tax.
Compound interestSee how savings grow with compound interest and regular contributions. Yearly breakdown of balance, deposits and interest earned.DiscountFind the sale price and how much you save from any percentage off. Also works backwards from the sale price to the discount.Effective rateTurn a nominal annual rate into the effective annual rate for any compounding frequency — the number that lets you compare offers fairly.GSTAdd GST to a net amount or strip it out of a gross one, with the tax, net and gross figures and the reverse formula shown.MortgageWork out your monthly payment, total interest and full amortisation schedule for any loan amount, rate and term.Sales taxAdd sales tax to a price or work backwards from a tax-included total, at whatever rate applies in your state or city.Simple interestCalculate simple interest on a principal over years, months or days, and see the interest and the total amount repayable.VAT / taxAdd tax to a net price or strip it out of a gross price at any rate. Shows the net, the tax and the gross side by side.
Electrical
Watts, amps, volts, kVA and energy cost.
Amps to kVAConvert amps to kilovolt-amps for single-phase and three-phase supplies — apparent power, so no power factor is needed.Amps to kWConvert amps to kilowatts for DC, single-phase and three-phase circuits. Enter current, voltage and power factor to read real power in kW.Amps to VAConvert amps to volt-amps for single-phase and three-phase circuits. Apparent power in VA is current times voltage — power factor does not apply.Amps to VoltsConvert amps to volts with Ohm's law, V = I × R. Enter the current and the resistance to get the voltage across the component.Amps to WattsConvert amps to watts for DC, single-phase and three-phase circuits. Enter the current and the voltage to get real power in watts.Electricity billWork out what an appliance costs to run per day, month and year from its wattage, hours of use and your tariff.Energy Consumption CalculatorWork out how much energy an appliance uses per day, month and year from its wattage and how many hours a day you run it.Energy Cost CalculatorTurn an appliance's wattage and daily run time into a real cost per day, month and year at your own price per kilowatt-hour.eV to VoltsConvert electron-volts to volts by dividing the energy by the charge in elementary charges. Useful in physics and semiconductor work.Joules to VoltsConvert joules to volts by dividing the energy by the charge in coulombs — one volt is one joule per coulomb.Joules to WattsConvert joules to watts by dividing the energy by the time in seconds — the average power delivered over that interval.kVA to AmpsConvert kVA to amps for single-phase and three-phase supplies — the standard way to size cables and breakers from a transformer or generator rating.kVA to kWConvert apparent power in kVA to real power in kilowatts by multiplying by the power factor. Shows the working and the reactive power too.kVA to VAConvert kilovolt-amps to volt-amps. The kilo prefix is a factor of 1000, so the conversion is exact and the power factor is irrelevant.kVA to WattsConvert kVA to watts: multiply the apparent power by the power factor, then by 1000. Gives the real power the load actually consumes.kW to AmpsConvert kilowatts to amps for DC, single-phase and three-phase supplies — the quickest way to size a breaker or a cable from a motor rating.kW to kVAConvert real power in kilowatts to apparent power in kVA by dividing by the power factor — the number you need when sizing a generator.kW to kWhConvert kilowatts to kilowatt-hours by multiplying the power by the running time — power is a rate, energy is the rate times hours.kW to VAConvert kilowatts to volt-amps: divide by the power factor and multiply by 1000. Shows the substitution so you can check it by hand.kW to VoltsFind the supply voltage from a kilowatt rating and the measured current, for DC, single-phase and three-phase circuits.kWh to kWConvert kilowatt-hours to kilowatts by dividing the energy used by the number of hours it took — the average power draw over that period.kWh to WattsConvert kilowatt-hours to watts: divide the energy by the time in hours and multiply by 1000 to get the average power in watts.Ohm's lawEnter any two of voltage, current, resistance or power and get the other two instantly, with the formula used shown.Power CalculatorCalculate electrical power from voltage and current, and see the equivalent resistance, energy per hour and power in kilowatts.Power Factor CalculatorWork out power factor from real power and apparent power, and see the phase angle and the reactive power that goes with it.VA to AmpsConvert volt-amps to amps for single-phase and three-phase supplies — useful for sizing UPS output cables and transformer secondaries.VA to kVAConvert volt-amps to kilovolt-amps by dividing by 1000. An exact conversion — no power factor and no phase assumptions involved.VA to kWConvert volt-amps to kilowatts by multiplying by the power factor and dividing by 1000 — apparent power to real power in one step.VA to WattsConvert volt-amps to watts by multiplying by the power factor. On a purely resistive load the two are equal; on a motor they are not.Voltage dividerCalculate the output voltage of a two-resistor divider, or find the resistor you need to hit a target voltage.Volts to AmpsConvert volts to amps using resistance — Ohm's law, I = V ÷ R. Enter the voltage and the resistance to get the current in amps.Volts to eVConvert volts to electron-volts by multiplying by the charge in elementary charges — the energy an electron gains crossing that potential.Volts to JoulesConvert volts to joules using the charge in coulombs. Voltage is energy per unit charge, so energy equals voltage times charge.Volts to kWConvert volts to kilowatts using the circuit current and power factor, for DC, single-phase and three-phase supplies.Volts to WattsConvert volts to watts using the circuit current. Covers DC, single-phase and three-phase supplies and shows the calculation step by step.Watts to AmpsConvert watts to amps for DC, single-phase and three-phase supplies. Enter the power and the voltage and read the current, with the working shown.Watts to JoulesConvert watts to joules by multiplying the power by the time in seconds. A watt is one joule per second, so the conversion is exact.Watts to kVAConvert watts to kVA by dividing the real power by the power factor and by 1000 — the figure to quote when specifying a UPS or generator.Watts to kWhConvert watts to kilowatt-hours: multiply the power by the hours it runs and divide by 1000. This is the number your electricity bill charges for.Watts to VAConvert watts to volt-amps by dividing by the power factor. The result is the apparent power a supply must be able to deliver.Watts to VoltsWork out the supply voltage from power and current for DC, single-phase and three-phase circuits, with the formula and the substitution shown.
Lighting
Lumens, lux, candela and watts.
Candela to LumensConvert candela to lumens using the beam's apex angle. Candela measures intensity in one direction; lumens measure the whole beam.Candela to LuxConvert candela to lux at a given distance. Illuminance falls with the square of distance, so doubling the range quarters the light.Footcandles to LuxConvert footcandles to lux. One footcandle is one lumen per square foot, which works out to 10.7639 lux exactly.Lumens to CandelaConvert lumens to candela using the beam angle. A narrow beam concentrates the same lumens into a much higher intensity.Lumens to LuxConvert lumens to lux by spreading the light over a surface area. Lux is illuminance: how bright the lit surface actually is.Lumens to MillicandelaConvert lumens to millicandela using the apex angle — the rating style used for indicator LEDs and small emitters.Lumens to WattsConvert lumens to watts using the lamp's luminous efficacy — the honest way to compare an LED bulb with the incandescent it replaces.Lux to CandelaConvert lux to candela at a measured distance — work back from a light-meter reading to the source's luminous intensity.Lux to FootcandlesConvert lux to footcandles by dividing by 10.7639 — the conversion between metric and US illuminance units.Lux to LumensConvert lux to lumens by multiplying illuminance by the lit area — how much total light output a room of a given brightness needs.Lux to WattsConvert lux to watts: multiply the target illuminance by the floor area, then divide by the lamp's lumens-per-watt efficacy.Millicandela to LumensConvert millicandela to lumens using the beam angle — turns an indicator LED's mcd rating into total light output.Watts to LumensConvert watts to lumens with the lamp's luminous efficacy. Shows how much light a bulb of a given wattage actually produces.Watts to LuxConvert watts to lux from the lamp's efficacy and the area being lit — a quick sanity check when planning room lighting.
Wire & cable
AWG, SWG and voltage drop.
AWG to mmConvert an American Wire Gauge number to a diameter in millimetres and a cross-section in mm², using the exact defining formula.SWG to mmConvert a British Standard Wire Gauge number to millimetres and mm², using the official SWG table rather than a formula.Voltage Drop CalculatorCalculate the voltage lost in a cable run from its gauge, length and current — and check it against the usual 3 % limit.Wire gauge chartFull AWG reference table: diameter in millimetres and inches, cross-section in mm², copper resistance per kilometre, and the SWG equivalent.
Grades
GPA, final grade and letter grades.
Final gradeFind out exactly what you need to score on the final exam to reach the grade you want, given your current grade and the exam's weight.GPACalculate your grade point average from course credits and letter grades on the standard 4.0 scale, with the working shown.GradeWork out your overall course grade from weighted assignments, exams and projects — and see the letter grade it lands on.Grade to GPAConvert a percentage to a letter grade and a letter grade to GPA points, with the full 4.0-scale conversion table below.
Time & Date
Age, date differences and durations.
AgeFind your exact age in years, months and days — plus total weeks, days, hours and your next birthday countdown.BirthdayCount down to your next birthday, see which day of the week you were born on, and how many days, weeks and hours you have been alive.Date differenceCount the days, weeks, months and working days between two dates — or add and subtract a duration from any date.Time calculatorAdd or subtract two durations in hours, minutes and seconds, and see the result in each unit — handy for timesheets and splits.
Health
Body metrics and fitness numbers.
Everyday
Tips, ratios and numbers in words.
Aspect ratioResize while keeping the proportions. Enter a width or height and get the matching dimension for 16:9, 4:3 or any custom ratio.Number to wordsWrite any number out in English words — in the international system (million, billion) or the South Asian one (lakh, crore).TipWork out the tip and split the bill between any number of people, with an option to round the total up.