Unit Converters
Convert between metric, US customary and imperial units. Every converter works both ways as you type and uses exact defined conversion factors.
Converter categories
Each category page converts between all of its units and links to dedicated pages for the most common conversions.
- Length ConverterConvert between mm, cm, m, km, inches, feet, yards, miles and nautical miles.
- Weight ConverterConvert kilograms, grams, pounds, ounces, stone and tons.
- Temperature ConverterConvert between Celsius, Fahrenheit and kelvin, including negative values.
- Area ConverterConvert square meters, square feet, acres, hectares and more.
- Volume ConverterLiters, milliliters, US and imperial gallons, cups, spoons and cubic units.
- Speed ConverterConvert km/h, mph, meters per second, knots and feet per second.
- Data Storage ConverterBytes, kilobytes, megabytes, gigabytes and terabytes — decimal and binary.
- Pressure Converterpsi, bar, kPa, pascals, atmospheres, millibars and mercury units.
- Angle ConverterDegrees, radians, gradians, arcminutes, arcseconds and turns.
- Fuel Economy ConverterConvert between US mpg, UK mpg, L/100 km and km/L.
Most-used conversions
- Centimeters to InchesConvert centimeters to inches with the formula and a quick table.
- Kilograms to PoundsConvert kilograms to pounds with the formula and a quick table.
- Degrees Celsius to Degrees FahrenheitConvert degrees Celsius to degrees Fahrenheit with the formula and a quick table.
- Feet to MetersConvert feet to meters with the formula and a quick table.
- Miles to KilometersConvert miles to kilometers with the formula and a quick table.
- Liters to US GallonsConvert liters to US gallons with the formula and a quick table.
- mph to km/hConvert miles per hour to kilometers per hour with the formula and a quick table.
- Square Meters to Square FeetConvert square meters to square feet with the formula and a quick table.
How accurate are the conversions?
Most imperial and US units are defined exactly in terms of metric units. Since 1959 an inch is exactly 2.54 cm and a pound is exactly 0.45359237 kg; a US gallon is exactly 231 cubic inches. CalcoraBase uses these definitions directly, so conversions are exact up to the display precision of about ten significant digits.
Watch for units that share a name: US and imperial gallons, pints and fluid ounces are different sizes, and a “ton” can mean a metric ton, a US short ton or a UK long ton. The US vs imperial units page lists the differences.
Time units
Hours, minutes and seconds conversions are in the Time & Date section — see the time unit converter.