Unit Conversion Cheat Sheet
Most conversions are a single multiplication. These are the factors worth remembering, and the exact definitions behind them.
Length
| Unit | Equals |
|---|---|
| 1 inch | 2.54 cm (exact) |
| 1 foot | 0.3048 m (exact) |
| 1 mile | 1.609344 km (exact) |
| 1 meter | 3.28084 feet |
Weight
| Unit | Equals |
|---|---|
| 1 pound | 0.45359237 kg (exact) |
| 1 ounce | 28.349523 g |
| 1 kg | 2.20462 pounds |
Volume
1 US gallon is 3.785411784 liters. A US gallon is not the same as an imperial (UK) gallon, which is about 4.546 liters, so check which one you need.
Temperature
Temperature does not convert with a single factor.
- Fahrenheit = Celsius × 9 ÷ 5 + 32. For example, 25 °C is 77 °F.
- Celsius = (Fahrenheit − 32) × 5 ÷ 9.
- Kelvin = Celsius + 273.15.
Fuel economy
Miles per gallon (US) and liters per 100 km are inverses of each other: L/100 km = 235.215 ÷ mpg. At 30 mpg that is about 7.84 L/100 km. A higher mpg is better, while a lower L/100 km is better.
Tips
- Convert in one step from the original number to avoid stacking rounding errors.
- Keep extra digits while you calculate and round only the final answer.