Unit Converter
Pick what you are converting, type a number and choose the two units. The result appears as you type, with the exact value when it is short, and a table shows the same value in every unit of that kind. It covers length, weight and mass, volume, area, speed, data size and time, in metric, US and UK units. Everything runs in your browser.
The same value in every length unit
| Meters | 1,609.344 | m |
| Kilometers | 1.609344 | km |
| Centimeters | 160,934.4 | cm |
| Millimeters | 1,609,344 | mm |
| Micrometers | 1,609,344,000 | um |
| Nanometers | 1,609,344,000,000 | nm |
| Miles | 1 | mi |
| Yards | 1,760 | yd |
| Feet | 5,280 | ft |
| Inches | 63,360 | in |
| Nautical miles | 0.8689762419 | nmi |
Every conversion is worked out with exact fractions of whole numbers, so there is no floating point error, and the result is written out in full when it ends within 20 decimals. The inch is exactly 25.4 millimeters, the pound exactly 0.45359237 kilograms and the US gallon exactly 231 cubic inches. US and UK gallons, pints and fluid ounces differ, and are listed separately. Data sizes are kept apart too: a gigabyte is 1,000,000,000 bytes and a gibibyte is 1,073,741,824. A year here is 365 days, because months and years vary in length. Nothing you enter is uploaded.
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Developer & WebAbout the Unit Converter
Every unit is stored as an exact fraction of a base unit, and a conversion multiplies whole numbers instead of decimals, so there is no floating point error. The definitions are the international ones: the inch is exactly 25.4 millimeters, so 1 inch is 2.54 centimeters; the pound is exactly 0.45359237 kilograms; the US gallon is exactly 231 cubic inches, which is 3.785411784 liters; and the acre is exactly 4,046.8564224 square meters. When the result ends within 20 decimals it is shown in full, so 1 gigabyte is exactly 953.67431640625 mebibytes, and otherwise it is rounded to 10 significant digits. You can also choose a fixed number of decimals, and the tool tells you whether the figure shown is exact. Units that sound alike but differ are listed separately. A US gallon is 3.785411784 liters and a UK gallon is 4.54609 liters, a US fluid ounce is about 29.57 milliliters and a UK one about 28.41. In data sizes, a kilobyte is 1,000 bytes and a kibibyte is 1,024, a gigabyte is 1,000,000,000 bytes and a gibibyte is 1,073,741,824, so a drive sold as 500 GB is 465.66 GiB. A year is 365 days here, because calendar years and months vary in length. Nothing you enter is uploaded.
How many centimeters are in an inch?▾
Exactly 2.54, because the inch is defined as 25.4 millimeters. So 10 inches is 25.4 centimeters, and a foot of 12 inches is 30.48 centimeters.
What is the difference between a US gallon and a UK gallon?▾
A US gallon is 3.785411784 liters and a UK, or imperial, gallon is 4.54609 liters, about 20 percent larger. Pints, quarts and fluid ounces differ in the same way, so the tool lists US and UK units separately.
What is the difference between a GB and a GiB?▾
A gigabyte (GB) is 1,000,000,000 bytes, and a gibibyte (GiB) is 1,073,741,824 bytes, which is 2 to the power of 30. A drive sold as 500 GB holds 500,000,000,000 bytes, which is 465.66 GiB, the figure many operating systems show.
How do I convert miles to kilometers?▾
Multiply by 1.609344, which is exact because the mile is defined as 1,609.344 meters. 5 miles is 8.04672 kilometers, and 100 kilometers per hour is about 62.137 miles per hour.
How accurate are the results?▾
The arithmetic is exact, using fractions of whole numbers, and the tool tells you when the value shown is the exact one. A result that never ends, such as 1 foot in miles, is rounded to 10 significant digits or to the decimals you choose.