What this unit converter covers
Ten kinds of measurement in one place: length, weight, temperature, volume, area, speed, data storage, time, pressure, energy. Each one includes the metric units, the US customary units and, where they differ, the British imperial ones. Type a value on the left or the right, and the other side updates. Below the result you see the same value in every unit of that kind, so you rarely need a second conversion.
How the conversion works
Every unit is stored by its size in one base unit, for example meters for length or kilograms for weight. To convert, the value is turned into the base unit and then into the target unit. Temperatures are the exception, because Celsius and Fahrenheit do not start at zero: they go through kelvin with the proper formulas.
Common conversions
| From | Equals |
|---|---|
| 1 inch | 2.54 centimeters |
| 1 foot | 0.3048 meters |
| 1 yard | 0.9144 meters |
| 1 mile | 1.609344 kilometers |
| 1 ounce | 28.34952313 grams |
| 1 pound | 0.45359237 kilograms |
| 1 stone | 6.35029318 kilograms |
| 1 US fluid ounce | 29.57352956 milliliters |
| 1 US cup | 236.5882365 milliliters |
| 1 US gallon | 3.785411784 liters |
| 1 UK gallon | 4.54609 liters |
| 1 square foot | 0.09290304 square meters |
| 1 acre | 0.4046856422 hectares |
| 1 mile per hour | 1.609344 kilometers per hour |
| 1 gibibyte | 1.073741824 gigabytes |
| 1 bar | 14.50377377 pounds per square inch |
| 1 kilocalorie | 4.184 kilojoules |
| 1 kilowatt-hour | 3,600 kilojoules |
How to use it
- 1Pick what you want to convert, for example Length or Temperature.
- 2Choose the units on both sides and type a value. You can type on either side, and the swap button turns the conversion around.
- 3Read the result, the conversion factor and the list of all other units. Tap a unit in the list to convert into it, or copy the result or a link.
Frequently asked questions
How exact are the conversions?
They use the official definitions, for example 1 inch = 2.54 cm and 1 pound = 0.45359237 kg exactly. Results are shown with up to 10 significant digits, which is more precise than any everyday measurement.
Why are US and UK gallons different?
Both come from older English measures, but the US kept the wine gallon of 231 cubic inches (3.785 liters) while the UK redefined its gallon in 1824 as 4.54609 liters. US and UK pints and fluid ounces differ for the same reason, so the converter lists them separately.
What is the difference between KB and KiB?
KB, MB and GB are decimal: 1 KB is 1,000 bytes. KiB, MiB and GiB are binary: 1 KiB is 1,024 bytes. Drive makers use decimal units, while some operating systems show binary sizes, which is why a 1 TB drive appears as about 931 GiB.
Why can I not just multiply temperatures?
Celsius and Fahrenheit have different zero points, so they need an offset as well as a factor: °F = °C × 9/5 + 32. Kelvin starts at absolute zero, so the converter rejects values below −273.15 °C.
How long is a month or a year in the time converter?
Months and years have different lengths, so the converter uses the average Gregorian values: a year of 365.2425 days and a month of one twelfth of that, about 30.44 days. For exact calendar spans, use the Days Between Dates tool.