Unit Converter
Convert between metric, imperial and US units in 11 categories. Type a value once and see it in every unit of the category.
INPUT
RESULT
- Millimetre (mm)1,000,000
- Centimetre (cm)100,000
- Metre (m)1,000
- Inch (in)39,370.07874
- Foot (ft)3,280.839895
- Yard (yd)1,093.613298
- Mile (mi)0.6213711922
- Nautical mile (nmi)0.5399568035
Runs entirely in your browser. Nothing you enter is sent to a server.
How to convert units
Choose a category
Pick what you're measuring, such as length, temperature or data size.
Enter the value
Type the number and choose its unit.
Read every unit
All other units of the category are listed at once. Use Copy next to the one you need.
Exact factors
Imperial and US units are defined in metric terms: an inch is exactly 25.4 mm, a pound 0.45359237 kg and a US gallon 3.785411784 litres. The converter uses these definitions and shows up to 10 significant digits.
US and UK units differ
A US gallon is smaller than a UK gallon, and the same goes for fluid ounces and miles per gallon. Data sizes also come in two kinds: a kilobyte (kB) is 1,000 bytes, a kibibyte (KiB) 1,024.
Frequently asked questions
How are temperatures converted?
With the exact formulas: °F = °C × 9/5 + 32, and K = °C + 273.15.
Why is a year 365 days?
Years and months vary in length, so the time category uses a 365-day year. For calendar dates, use the Date Difference Calculator.
How does fuel economy convert?
Litres per 100 km go down as a car gets more efficient, while km/L and mpg go up, so the conversion is an inverse. 5 L/100 km is 20 km/L, or about 47 US mpg.