Unit Conversion Calculators
These converters bridge the gap between the metric system used by most of the world and the customary units used in the United States. Whether you are reading an international product label, following a forecast in Celsius, or planning a trip measured in kilometers, each workbench converts in any direction across every supported unit, uses the exact internationally defined factor, and includes a quick-reference table for common values.
Multi-unit converters
Deep workbenches that convert in any direction across every unit at once — with the formula, the substituted equation, all units side by side, and a reference table.
- Temperature ConverterFree temperature converter between Celsius, Fahrenheit, and Kelvin. Pick any source and target scale, see all three at once, the exact formula, the substituted equation, and a reference table.
- Weight & Mass ConverterFree weight and mass converter between kilograms, pounds, grams, ounces, milligrams, metric tons, and US tons. Pick any two units, see all units at once, the exact factor, and a reference table.
- Length & Distance ConverterFree length and distance converter between miles, kilometers, meters, feet, inches, yards, centimeters, and millimeters. Pick any two units, see all units at once, the exact factor, and a reference table.
Weight and mass
The pound is defined as exactly 0.45359237 kilograms, so weight conversions are precise rather than approximate. Going from kilograms to pounds you multiply by about 2.205; going the other way you divide by the same figure. These come up constantly with body weight, luggage allowances, and shipping. The Weight & Mass Converter handles kilograms, pounds, grams, ounces, tons, and more in both directions.
Length and distance
One mile equals exactly 1.609344 kilometers. Distance conversions are purely proportional, which makes them straightforward for road signs, race lengths, and maps. Runners in particular meet these numbers at every metric race distance. The Length & Distance Converter covers miles, kilometers, meters, feet, inches, yards, and centimeters.
Temperature
Temperature is the one conversion in this group that is not a simple multiplication, because the scales start at different points. You rescale the degree size with a 9/5 or 5/9 factor and adjust for the offset. The Temperature Converter handles Celsius, Fahrenheit, and Kelvin in any direction and shows why the order of steps matters.
Conversion results are for general informational use. See our Methodology for how these tools are built.