Common conversions cheat sheet
The conversions people look up most, with the exact definition behind each one, on one printable page.
The conversions people look up most, with the exact definition behind each one. Where a value is a definition (such as 1 inch = 2.54 cm) it is exact; other values are rounded to the figures shown.
Length
Weight
Volume
| From | To | Multiply by |
|---|---|---|
| 1 US gallon | 3.785412 litres | 3.785412 |
| 1 UK gallon | 4.54609 litres (exact) | 4.54609 |
| 1 UK pint | 0.568261 litres | 0.568261 |
| 1 US fluid ounce | 29.573530 ml | 29.57353 |
| 1 UK fluid ounce | 28.413063 ml | 28.413063 |
| 1 US cup | 236.588 ml | 236.588 |
Temperature
| Celsius | Fahrenheit | Where you meet it |
|---|---|---|
| 0 °C | 32 °F | Water freezes |
| 20 °C | 68 °F | Room temperature |
| 37 °C | 98.6 °F | Normal body temperature |
| 100 °C | 212 °F | Water boils at sea level |
| -40 °C | -40 °F | The scales meet |
Celsius to Fahrenheit: multiply by 9/5 and add 32. Fahrenheit to Celsius: subtract 32 and multiply by 5/9.
Speed and area
| From | To | Multiply by |
|---|---|---|
| 1 mph | 1.609344 km/h | 1.609344 |
| 1 knot | 1.852 km/h (exact) | 1.852 |
| 1 acre | 0.404686 hectares | 0.404686 |
| 1 square metre | 10.7639 square feet | 10.7639 |
Quick mental checks
- cm to inches: divide by 2.5 for a close answer (exact is 2.54).
- km to miles: multiply by 0.6 (exact is 0.621371).
- kg to pounds: double it and add 10% (exact is 2.20462).
- °C to °F: double it and add 30 for a rough answer; use ×9/5 + 32 for the exact figure.
Frequently asked questions
Which conversion factors are exact?
Definitions such as 1 inch = 2.54 cm, 1 pound = 0.45359237 kg, 1 mile = 1.609344 km and 1 UK gallon = 4.54609 litres are exact. Factors shown with fewer digits are rounded.
What is the easy way to convert Celsius to Fahrenheit?
Multiply by 9/5 and add 32. For a rough mental answer, double the Celsius figure and add 30.
Is a US gallon the same as a UK gallon?
No. A US gallon is 3.785 litres and a UK (imperial) gallon is 4.546 litres, so the UK gallon is about 20% larger.