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Unit Converter

Convert between 87 units across ten measurement families, and see the same value in every other unit of that family at once.

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How to use Unit Converter — Length, Weight, Temperature

  1. 1Pick the kind of measurement, then the unit you are converting from and to.
  2. 2Type your value — the result updates as you type.
  3. 3Scroll down for the same value in every other unit, and a table of common conversions.

About Unit Converter

Most converters answer one question and stop. This one shows the whole family, because the number you actually need is often next to the one you asked for: convert 42 cm and you also get it in millimetres, metres, inches, feet and yards without changing anything. That single view is what makes a conversion page worth keeping open while you work.

The factor tables behind it are deliberately pedantic about the traps. US and Imperial gallons, pints and fluid ounces are separate entries rather than one averaged "gallon". Decimal kilobytes and binary kibibytes are both present and labelled with their multiplier. Mach is marked as being at sea level, because the speed of sound changes with temperature and altitude. Months and years are labelled as averages so nobody mistakes them for calendar arithmetic.

Temperature gets its own path through the maths. Every other unit here converts with one multiplication, but Celsius, Fahrenheit, Kelvin and Rankine each have a different zero point, so converting them means shifting as well as scaling. Treating temperature like a ratio is the single most common conversion mistake, and it is the reason this tool never shows a "1 °C = x °F" rate card the way it does for metres and kilograms.

Frequently asked questions

Which units are covered?
Ten families and 87 units: length (11, from nanometres to nautical miles), weight (9, including stone and both tons), area (10), volume (16), speed (6), data (10), time (8), pressure (6), energy (7) and temperature (4 scales — Celsius, Fahrenheit, Kelvin and Rankine).
Why are US and Imperial gallons listed separately?
Because they are different sizes. A US gallon is 3.785412 litres and an Imperial gallon is 4.54609 litres — about 20% larger. The same split applies to pints and fluid ounces, so both versions are listed by name instead of one ambiguous "gallon".
Is a kilobyte 1000 or 1024 bytes?
Both are real units, so both are listed. KB, MB, GB and TB use powers of 1000; KiB, MiB, GiB and TiB use powers of 1024. That difference is why a drive sold as 1 TB shows as roughly 931 GiB in your operating system — 1 GB is 0.9313225746 GiB.
Why is temperature handled differently from the other families?
Temperature scales have an offset as well as a scale factor, so they are not simple ratios. 1 °C is 33.8 °F, but a rise of 1 °C is a rise of 1.8 °F. Because of that, the converter hides the "1 unit equals" ratio cards for temperature — they would be misleading.
Can I convert months and years?
Yes, but they are averages, not calendar arithmetic. A month here is 2,629,746 seconds (30.44 days) and a year is 31,556,952 seconds, both taken from the 400-year Gregorian cycle. For the number of days between two real dates, use a date calculator instead.
How accurate are the answers?
The factors are the exact defined values — 1 inch is exactly 2.54 cm, 1 pound is exactly 0.45359237 kg — so no precision is lost in the conversion itself. Only the display is rounded, to at most 10 decimal places, switching to scientific notation for numbers below 0.000001 or above 10^15.