Free online calculators and unit converters for percent, money, health, math, dates and more

Calculators and converters, each with the answer as you type and the worked steps underneath: loans and interest, BMI and calories, fractions and statistics, dates and time zones, concrete and paint, and exact unit conversions.

Percent of a number Percent change Discount °C to °F Tip

Percent calculators

All percent calculators ›

Percentage calculatorFind a percent of any number, such as 15% of 200.Open the calculator ›What percent is X of YTurn a part and a whole into a percent, such as 30 out of 200.Open the calculator ›X is Y% of what numberFind the whole when you know a part and its percent.Open the calculator ›Percent change calculatorPercent increase or decrease from an old value to a new value.Open the calculator ›Percent increase calculatorAdd a percent to a number, such as 200 plus 15%.Open the calculator ›Percent decrease calculatorTake a percent off a number, such as 200 minus 15%.Open the calculator ›

Everyday calculators

All everyday calculators ›

Grade percentage calculatorTurn points earned out of points possible into a percent.Open the calculator ›Discount calculatorSale price and savings from an original price and a percent off.Open the calculator ›Sales tax calculatorAdd sales tax at the rate you enter to any price.Open the calculator ›Tip calculatorTip, total and the amount each person pays.Open the calculator ›Markup and margin calculatorProfit, margin and markup from a cost and a selling price.Open the calculator ›

Finance calculators

All finance calculators ›

Commission calculatorCommission earned on sales, with optional base pay.Open the calculator ›

Health and fitness calculators

All health and fitness calculators ›

Time and date calculators

All time and date calculators ›

Age calculatorExact age in years, months and days, plus total days and the next birthday.Open the calculator ›Day of the week calculatorWhat weekday any date falls on, with day of year and ISO week.Open the calculator ›

Home, school and electrical calculators

All home, school and electrical calculators ›

Mulch calculatorMulch needed to cover a garden bed to a chosen depth.Open the calculator ›Cubic yard calculatorVolume in cubic yards from length, width and depth in any unit.Open the calculator ›Volts, amps and watts calculatorFind watts, amps or volts from the other two.Open the calculator ›Voltage drop calculatorVoltage drop over a wire run from AWG size, length and current.Open the calculator ›pH calculatorConvert between pH, pOH, hydrogen ion and hydroxide concentration.Open the calculator ›

Math calculators

All math calculators ›

Mean calculatorArithmetic mean (average) of a list of numbers.Open the calculator ›Divisibility calculatorCheck which of 2 to 12 divide a number, with the rules.Open the calculator ›Cross product calculatorCross product, dot product, magnitude and angle of two 3D vectors.Open the calculator ›Prime factorization calculatorBreak a number into prime factors, and count its divisors.Open the calculator ›Factorial calculatorn factorial, exact for any n up to 170.Open the calculator ›Percent error calculatorHow far a measured value is from the true value, as a percent.Open the calculator ›

Geometry calculators

All geometry calculators ›

Trapezoid area calculatorArea and median of a trapezoid from its parallel sides and height.Open the calculator ›Pythagorean theorem calculatorFind the hypotenuse or a missing leg of a right triangle.Open the calculator ›Ellipse calculatorArea, perimeter, eccentricity and focal distance of an ellipse.Open the calculator ›

Temperature converters

All temperature converters ›

Celsius to FahrenheitConvert °C to °F with the worked formula.Open the calculator ›Fahrenheit to CelsiusConvert °F to °C with the worked formula.Open the calculator ›Temperature converter (°C, °F, K)Convert between Celsius, Fahrenheit and Kelvin in one place.Open the calculator ›

Unit converters

All unit converters ›

Length converterMetres, kilometres, inches, feet, yards, miles and nautical miles.Open the calculator ›Weight converter (mass)Kilograms, grams, pounds, ounces, stones and tons.Open the calculator ›Energy converterJoules, kilojoules, calories, watt-hours, kilowatt-hours, BTU and more.Open the calculator ›Power converterWatts, kilowatts, megawatts, horsepower and BTU per hour.Open the calculator ›Frequency converterHertz, kilohertz, megahertz, gigahertz, terahertz and revolutions per minute.Open the calculator ›Voltage converterMicrovolts, millivolts, volts, kilovolts and megavolts.Open the calculator ›