Unit Converter
Convert length, weight, temperature, volume, area, speed, time and data units.
Volume uses US measures unless marked UK. Months and years use average lengths.
How to use the unit converter
This free unit converter handles eight types of measurement in one place: length, weight, temperature, volume, area, speed, time and data storage. It's useful for cooking, travel, school, DIY projects and work.
- Choose what you want to convert, such as length or temperature.
- Enter a value and choose the unit you're converting from.
- Choose the unit you're converting to. Tap the ⇅ button to swap them.
You'll see the answer instantly, plus a table showing your value in every unit of that type.
Common conversions at a glance
Length
| From | To | Multiply by |
|---|---|---|
| Inches | Centimeters | 2.54 (exact) |
| Feet | Meters | 0.3048 (exact) |
| Miles | Kilometers | 1.609344 (exact) |
| Meters | Feet | 3.28084 |
| Kilometers | Miles | 0.621371 |
Weight and mass
| From | To | Multiply by |
|---|---|---|
| Pounds | Kilograms | 0.45359237 (exact) |
| Kilograms | Pounds | 2.20462 |
| Ounces | Grams | 28.3495 |
| Stone | Pounds | 14 (exact) |
Volume (US measures)
| From | To | Multiply by |
|---|---|---|
| Gallons | Liters | 3.78541 |
| Cups | Milliliters | 236.588 |
| Fluid ounces | Milliliters | 29.5735 |
| Tablespoons | Teaspoons | 3 (exact) |
US and UK (imperial) volumes are different. A UK gallon is about 4.546 liters, around 20% bigger than a US gallon. The converter uses US measures unless the unit is marked UK.
Temperature conversion formulas
Temperature can't be converted with a single multiplier, because the scales start at different points:
| Reference point | Celsius | Fahrenheit |
|---|---|---|
| Water freezes | 0 °C | 32 °F |
| Room temperature | About 20–22 °C | About 68–72 °F |
| Normal body temperature | About 37 °C | About 98.6 °F |
| Water boils (at sea level) | 100 °C | 212 °F |
| Same on both scales | −40 °C | −40 °F |
A quick mental trick for Celsius to Fahrenheit: double it and add 30. It's not exact, but it's close for everyday weather.
Data storage: KB vs. KiB
Storage sizes can be measured in two ways, which is why a new "1 TB" drive often shows less space on a computer.
- Decimal units (KB, MB, GB, TB) use powers of 1,000. 1 GB = 1,000,000,000 bytes. Drive makers use these.
- Binary units (KiB, MiB, GiB) use powers of 1,024. 1 GiB = 1,073,741,824 bytes. Many operating systems use these, sometimes labeled as "GB".
So a 1 TB drive holds about 931 GiB, even though nothing is missing.
Metric vs. imperial
Most of the world uses the metric system (meters, kilograms, liters), which is based on powers of 10 and easy to scale. The United States mainly uses US customary units (feet, pounds, gallons), and the UK uses a mix. Since 1959, inches, feet, yards, miles and pounds have been officially defined using metric values, which is why some conversions are exact.
Frequently asked questions
How many centimeters are in an inch?
There are exactly 2.54 centimeters in an inch. So 12 inches (1 foot) is 30.48 centimeters.
How do I convert Celsius to Fahrenheit?
Multiply by 9/5 (or 1.8) and add 32. For example, 25 °C × 1.8 + 32 = 77 °F.
How many pounds are in a kilogram?
One kilogram is about 2.20462 pounds. One pound is exactly 0.45359237 kilograms.
Why does my 1 TB hard drive show less space?
Drive makers count 1 TB as 1,000,000,000,000 bytes, but many computers count in binary units of 1,024. That makes the same drive show as about 931 "GB".
Are cups and gallons the same in the US and UK?
No. UK (imperial) gallons and pints are larger than US ones. This converter uses US measures unless the unit is marked UK.