Unit Converter
Convert a measurement between any two units, and see its value in every other unit of the same kind at a glance. Ten categories cover everyday and technical needs.
- Runs in your browser
- No sign-up
- Free to use
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How to use Unit Converter
- Choose a category such as Length, Weight or Temperature.
- Enter the value and pick the unit you are converting from.
- Pick the unit you are converting to; the result appears immediately.
- Scan the table below for the same value in all other units, or swap the two units with one click.
Unit Converter features
Ten categories
Length, weight, temperature, area, volume, speed, time, digital storage, pressure and energy.
All units at once
A table shows the value converted to every unit in the category.
Exact definitions
Conversions use the official factors, such as 1 inch = 2.54 cm exactly.
Swap button
Reverse the direction of a conversion instantly.
Sensible rounding
Results show enough significant digits to be useful without false precision.
Works offline once loaded
All calculations happen in your browser.
When to use Unit Converter
- Converting a recipe between cups, millilitres and grams of liquid.
- Translating height and weight between metric and imperial for a form.
- Checking a temperature in Celsius or Fahrenheit while travelling.
- Converting file sizes, speeds or pressures for technical work.
Unit Converter FAQ
How accurate are the conversions?
They use the exact legal definitions where one exists (for example, 1 pound = 0.45359237 kg) and are computed in double-precision arithmetic, which is accurate to about 15 significant digits. Results are displayed rounded to a sensible number of digits.
Why are US and UK gallons different?
They are different units with the same name. A US liquid gallon is 3.785 litres and an imperial (UK) gallon is 4.546 litres. The same applies to pints, quarts and fluid ounces, so both versions are listed separately.
What is the difference between MB and MiB?
A megabyte (MB) is 1,000,000 bytes, using decimal prefixes. A mebibyte (MiB) is 1,048,576 bytes, using binary prefixes. Drive makers use decimal units while operating systems often report binary ones, which is why a “500 GB” drive shows as about 465 GiB.
How is temperature converted?
Temperature scales have different zero points, so conversion needs an offset as well as a factor: °F = °C × 9 ÷ 5 + 32, and K = °C + 273.15.
Can it convert weight to volume?
Not directly, because that depends on the density of the substance: a cup of flour weighs far less than a cup of honey. Convert within one category at a time.
Metric, imperial and why both persist
Most of the world uses the International System of Units (SI), in which units scale by powers of ten: a kilometre is a thousand metres, a kilogram a thousand grams. The United States, and to a lesser extent the United Kingdom, still use customary and imperial units in daily life, where a mile is 5,280 feet and a pound is 16 ounces.
Since 1959 the imperial and US customary units of length and mass have been defined in terms of metric ones, which is why conversion factors such as 2.54 centimetres per inch are exact rather than approximations. Volume is the exception: the US and imperial systems kept different gallons, so a recipe or fuel-economy figure needs to specify which is meant.