All tools
Find a calculator, convert a unit, or explore a formula. Each tool includes a method and a worked example.
Percentage calculator
Find a percentage of any number. Calculate discounts, portions and everyday percentages with precise decimal arithmetic.
Open toolPercentage change calculator
Find how much one number is bigger or smaller than another in percent. Use this calculator to compare two values or measure a percentage increase or decrease, with the original value as your reference.
Open toolFactorial calculator
Calculate exact factorials from 0 to 1,000, including integers much larger than ordinary floating-point numbers can represent.
Open toolCompound interest calculator
See how a starting balance grows with compound interest. Compare rates, time horizons and compounding frequencies.
Open toolLoan payment calculator
Estimate a fixed monthly loan payment, total interest and total repayment from a loan amount, annual rate and term.
Open toolProfit margin calculator
Calculate gross profit and profit margin from your cost and selling price. Understand how much of each sale you keep.
Open toolCircle area calculator
Find the area and circumference of a circle from its radius. Use any consistent length unit.
Open toolPythagorean theorem calculator
Find the hypotenuse of a right triangle from the lengths of its two perpendicular sides.
Open toolConcrete calculator
Estimate concrete volume for a rectangular slab and include an allowance for waste. Enter all dimensions in metres.
Open toolDate difference calculator
Count the calendar days between two dates, with leap years handled automatically and no timezone shift.
Open toolLength converter
Convert metric and imperial distances, including metres, feet, inches and miles.
Open toolArea converter
Convert areas for land, floors and surfaces between metric and imperial units.
Open toolVolume converter
Convert liquid and solid volumes. Gallons here are US liquid gallons.
Open toolMass converter
Convert kilograms, grams, pounds and ounces using international avoirdupois definitions.
Open toolTime converter
Convert durations between seconds, minutes, hours and fixed 24-hour days.
Open toolTemperature converter
Convert Celsius, Fahrenheit and Kelvin with the correct offsets, not just a scale factor.
Open toolSpeed converter
Convert speed between metres per second, kilometres per hour and miles per hour.
Open toolPressure converter
Convert pressure readings between pascals, kilopascals, bars and pounds per square inch.
Open toolEnergy converter
Convert joules, kilojoules, kilowatt-hours and thermochemical calories.
Open toolPower converter
Convert power ratings between watts, kilowatts and megawatts.
Open toolData size converter
Convert bits and bytes with an explicit distinction between decimal and binary prefixes.
Open toolFuel economy converter
Convert fuel consumption in litres per 100 kilometres to miles per US gallon.
Open toolCentimetres to inches
Convert centimetres to inches for screens, sewing and everyday measurements. View common sizes and reverse the conversion.
Open toolKilograms to pounds
Convert kilograms to pounds for luggage, equipment and everyday weights. Compare common values and switch direction.
Open toolDistance, speed & time calculator
Solve for any one variable in distance = speed × time. Enter the other two quantities in the stated SI units.
Open toolDensity, mass & volume calculator
Solve for any one variable in density = mass ÷ volume. Enter the other two quantities in the stated SI units.
Open toolPressure, force & area calculator
Solve for any one variable in pressure = force ÷ area. Enter the other two quantities in the stated SI units.
Open toolPower, energy & time calculator
Solve for any one variable in power = energy ÷ time. Enter the other two quantities in the stated SI units.
Open toolBasic calculator
Add, subtract, multiply or divide two numbers. Decimal arithmetic keeps everyday calculations such as 0.1 + 0.2 precise.
Open toolFraction calculator
Add, subtract, multiply or divide two fractions and get an exact answer reduced to its simplest form.
Open toolGCD calculator
Find the greatest common divisor of two integers, including exact values beyond ordinary floating-point precision.
Open toolLCM calculator
Find the least common multiple of two integers using exact integer arithmetic. Negative inputs are handled by magnitude.
Open toolCombination calculator
Count the ways to choose r distinct items from n items when order does not matter and repetition is not allowed.
Open toolPermutation calculator
Count ordered selections of r distinct items from n items. Each item can appear only once in a selection.
Open toolProportion calculator
Solve a proportion of the form a/b = c/x. Find the missing fourth term from three nonzero numbers.
Open toolAverage calculator
Calculate the arithmetic mean, median, minimum and maximum of a list of numbers. Decimal values and negative numbers are supported.
Open toolWeighted average calculator
Find an average when values contribute different weights. Pair each value with its weight in the same list position.
Open toolWhat percent calculator
Find what percentage one number is of another. Compare a part with a nonzero whole using precise decimal arithmetic.
Open toolReverse percentage calculator
Recover an original value from a final value and a known percentage change. Enter a negative percentage for a decrease.
Open toolDiscount calculator
Calculate a discounted price and the amount saved from an original price and a discount percentage between 0 and 100.
Open toolMarkup calculator
Calculate the percentage added to a product’s cost and the gross profit at a given selling price.
Open toolBreak-even calculator
Find the minimum whole number of units to sell to cover fixed costs, using a constant selling price and variable cost per unit.
Open toolROI calculator
Calculate a simple return on investment from your total investment cost and total proceeds, including any income you choose to include.
Open toolSimple interest calculator
Calculate interest earned or owed when interest is based only on the starting principal, without compounding.
Open toolRectangle calculator
Find a rectangle’s area, perimeter and diagonal from its length and width. Keep both dimensions in the same unit.
Open toolTriangle area calculator
Calculate the area of a triangle from a base and its perpendicular height. Both measurements must use the same length unit.
Open toolCylinder calculator
Calculate the volume and total surface area of a right circular cylinder using its radius and perpendicular height.
Open toolSphere calculator
Find the volume and surface area of a sphere from its radius. Enter a consistent length measurement for the radius.
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