Common conversions
| From | To | Multiply by |
|---|---|---|
| inches | centimeters | 2.54 |
| feet | meters | 0.3048 |
| miles | kilometers | 1.609344 |
| pounds | kilograms | 0.45359237 |
| ounces | grams | 28.3495 |
| US gallons | liters | 3.78541 |
| square feet | square meters | 0.092903 |
| acres | square feet | 43,560 |
Temperature
°C = (°F − 32) × 5 ÷ 9 °F = °C × 9 ÷ 5 + 32
A quick estimate: double the Celsius temperature and add 30. 20 °C is about 70 °F (exactly 68 °F).
US customary vs. metric
The United States uses customary units such as inches, pounds, and gallons for most everyday things, while science, medicine, and most other countries use metric. Since 1959 the inch has been defined as exactly 2.54 centimeters and the pound as exactly 0.45359237 kilograms, so conversions are exact.
Watch out for gallons and ounces
- A US gallon (3.785 liters) is smaller than an imperial gallon (4.546 liters) used in the UK.
- A fluid ounce measures volume; an ounce measures weight. A cup of flour and a cup of water weigh very different amounts.
- Temperature isn't a simple ratio: °F = °C × 9/5 + 32.
Frequently asked questions
Is a US gallon the same as a UK gallon?
No. A US gallon is about 3.785 liters; an imperial (UK) gallon is about 4.546 liters. This converter uses US units.
How many cups are in a liter?
About 4.23 US cups. Choose Volume and convert liters to cups.