Unit converter for everyday measurements
Pick length, weight or temperature, enter a value and this unit converter instantly shows the result in the unit you need.
Last updated
How to use the unit converter
- Choose Length, Weight or Temperature.
- Type the value you want to convert.
- Pick the unit you are converting from and the unit you want.
- Read the answer, which updates as you type. Press the swap button to reverse the conversion.
How the unit converter works
Length and weight are converted through a base unit. Every length unit is stored as a number of metres and every weight unit as a number of grams, so any pair converts in two steps without a separate rule for each combination.
Temperature is different, because the scales don't share a zero point: 0 °C is 32 °F. The converter therefore uses formulas, going through Celsius, and refuses temperatures below absolute zero.
Formula
Length and weight: result = value × factor of the starting unit ÷ factor of the target unit. The factors are exact international definitions, including 1 inch = 0.0254 m, 1 foot = 0.3048 m, 1 mile = 1,609.344 m, 1 pound = 453.59237 g and 1 ounce = 28.349523125 g.
Temperature: °F = °C × 9 ÷ 5 + 32, °C = (°F − 32) × 5 ÷ 9, and K = °C + 273.15.
Example
10 kilometres is 10 × 1,000 ÷ 1,609.344, about 6.2137 miles, which is the distance of a 10K race.
A body temperature of 37 °C is 37 × 9 ÷ 5 + 32 = 98.6 °F, and 70 kg is 70,000 ÷ 453.59237, about 154.32 pounds.
Tips and common mistakes
Weight ounces are not fluid ounces
Fluid ounces measure volume. The ounce in this converter is the weight ounce, so don't use it for liquids in a recipe.
Round to a sensible precision
Results show up to six decimal places. Round to what the job needs; a road trip doesn't need distances to the millimetre.
Heights in feet and inches
Convert the feet and the inches separately and add the two results. With your height in centimetres and weight in kilograms, you can use the BMI calculator.
US paper sizes
Change inches to millimetres here, then enter them in the paper weight calculator to find a sheet's weight.
Frequently asked questions
Are the conversions exact?
Yes. Imperial units are defined exactly in metric terms, and results are shown to six decimal places.
How many centimetres are in an inch?
Exactly 2.54 centimetres, by international agreement since 1959.
How do I convert kilograms to pounds?
Divide the number of grams by 453.59237, or multiply kilograms by about 2.20462.
Why can't I enter −300 °C?
Nothing can be colder than absolute zero, −273.15 °C or 0 K, so the converter shows a message instead of an impossible result.
Which units are included?
Millimetres, centimetres, metres, kilometres, inches, feet, yards and miles; grams, kilograms, pounds and ounces; and Celsius, Fahrenheit and Kelvin.