How to use the Unit Converter tool
- Choose a categoryPick Length, Weight, Temperature, Area, Volume, Speed, Time or Data.
- Enter a valueType the number you want to convert. Decimals and scientific notation such as 1e6 work.
- Select the unitsChoose the units to convert from and to. Use ⇄ to swap them.
- Read the resultThe answer appears instantly with the conversion factor, plus a table of the value in every other unit.
Features
- Everyday and technical unitsFrom teaspoons and stones to nautical miles, knots and gibibytes.
- Exact definitionsUses the internationally defined factors, such as 1 inch = 2.54 cm exactly.
- Every unit at onceA table shows your value converted into all units of the category.
- Clear formulasTemperature conversions show the formula used, so you can check the math.
- Fast and offline-friendlyAll calculations happen in your browser as you type.
Common conversions at a glance
| From | To | Multiply by |
|---|---|---|
| Inches | Centimeters | 2.54 (exact) |
| Feet | Meters | 0.3048 (exact) |
| Miles | Kilometers | 1.609344 (exact) |
| Pounds | Kilograms | 0.45359237 (exact) |
| Kilograms | Pounds | about 2.20462 |
| US gallons | Liters | 3.785411784 (exact) |
| Acres | Square feet | 43,560 |
| km/h | mph | about 0.621371 |
Temperature formulas
Temperature scales have different zero points, so they need a formula instead of a single factor:
- Celsius to Fahrenheit: °F = °C × 9/5 + 32. So 100 °C = 212 °F, and 37 °C = 98.6 °F.
- Fahrenheit to Celsius: °C = (°F − 32) × 5/9.
- Celsius to Kelvin: K = °C + 273.15. Zero kelvin, absolute zero, is the lowest possible temperature.
Quick mental trick: to estimate °F from °C, double it and add 30. 20 °C ≈ 70 °F (exact: 68 °F).
US vs UK (imperial) units
Some units share a name but not a size. A US gallon is 3.785 liters, while a UK (imperial) gallon is 4.546 liters, about 20% more. A US short ton is 2,000 pounds, while a UK long ton is 2,240 pounds and a metric tonne is 1,000 kg. US cups, pints and fluid ounces also differ from their imperial versions. This converter labels each one clearly.
KB vs KiB: why your drive looks smaller
Storage makers use decimal units: 1 GB = 1,000,000,000 bytes. Many operating systems count in binary units: 1 GiB = 1,073,741,824 bytes, but often label them “GB”. That is why a “1 TB” drive shows up as about 931 GB in Windows. Nothing is missing; it’s the same number of bytes counted two ways. Internet speeds use bits, not bytes: a 100 Mbps connection downloads at most 12.5 MB per second.
Months and years
Months and years vary in length, so this converter uses averages from the Gregorian calendar: a year of 365.2425 days and a month of one-twelfth of that, about 30.44 days. For exact differences between two dates, use the Age Calculator. For body measurements, try the BMI Calculator, which accepts both metric and imperial units.