Unit conversion
Length, weight, volume, area, speed and temperature, both directions.
20 calculators
- Length ConverterPick the two units and the amount. Every other unit is listed underneath, because the one you want next is usually not the one you picked.
- Weight ConverterPounds to kilograms is the one people come for. The rest of the table is underneath, including stones and both kinds of ton.
- Volume ConverterKitchen and fuel-pump volumes in one table. These are US measures, which matters: a US gallon and pint are both smaller than the British ones.
- Area ConverterSquare feet to square meters for floors, acres to hectares for land. The trap with area units is that the conversion is the length factor squared, not the length factor.
- Speed ConverterMiles per hour to kilometers per hour for driving abroad, knots for anything on water, meters per second for physics homework.
- Temperature ConverterFahrenheit, Celsius and Kelvin. Unlike every other conversion, these scales start in different places, so there is an offset as well as a factor.
- Feet to Inches ConverterFeet to inches is the one conversion that is exact and needs no rounding: twelve inches to the foot, by definition.
- Inches to Feet ConverterInches to feet is a division by twelve. The answer usually lands on a decimal, which is what a tape measure never shows you.
- Feet to Meters ConverterA foot is 0.3048 meters exactly. That factor is a definition, not a measurement, so this conversion is precise however far you carry it.
- Miles to Kilometers ConverterA mile is 1.609344 kilometers exactly. Most people meet this conversion on a race entry or a foreign speed limit sign.
- Pounds to Kilograms ConverterA pound is 0.45359237 kilograms exactly. Body weight is the usual reason to convert it, and the usual reason the answer needs to be right.
- Ounces to Grams ConverterAn ounce is 28.3495 grams. Baking is where this conversion earns its keep, because grams are the only honest way to measure flour.
- Gallons to Liters ConverterA US gallon is 3.785 liters. These are US gallons, which are noticeably smaller than the imperial gallon still used in the UK.
- Fahrenheit to Celsius ConverterSubtract 32, then multiply by five ninths. The subtraction is the part people forget, and it is the part that matters.
- Centimeters to Inches ConverterA centimeter is exactly 0.393701 inches, so this is a division by 2.54. Heights, screen sizes and anything shipped from outside the US arrive in centimeters.
- Millimeters to Inches ConverterA millimeter is exactly 1/25.4 of an inch. This is the conversion that turns up on drill bits, fasteners, plywood and anything with a metric part in an imperial machine.
- Meters to Feet ConverterA meter is 3.28084 feet. It is the conversion for a foreign height, a pool length, a room on a European floor plan, or anything an altimeter reports.
- Kilometers to Miles ConverterA kilometer is 0.621371 miles. Race distances, foreign road signs and every car odometer outside the US arrive in kilometers.
- Kilograms to Pounds ConverterA kilogram is 2.2046226 pounds. Body weight, luggage limits and gym plates are the three places an American meets kilograms.
- Celsius to Fahrenheit ConverterMultiply by nine fifths, then add 32. The addition is the part people forget, and it is the part that turns a mild day into a freezing one.
Converting units
Each converter works in both directions and between metric and US customary units, with the exact conversion factor shown. Length, weight, volume, area and speed each have their own converter, because each uses a different set of units.
Temperature is the one conversion that is not a simple multiplication: Fahrenheit and Celsius start from different zero points. The temperature converters show the full formula, and the quick rule that 0°C is 32°F and every 5°C is 9°F.
Watch for units that share a name but differ in size. A US gallon is smaller than an imperial gallon, and a US ton is lighter than a metric tonne.