Fuel Economy Converter
Convert miles per gallon to liters per 100 km and back, plus UK mpg, km per liter and gallons per 100 miles.
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In Every Unit
| Unit | Value |
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How to Convert Fuel Economy Units
Miles per gallon and km per liter measure distance per fuel, so they convert by a factor. Liters per 100 km and gallons per 100 miles measure fuel per distance, so they are the reciprocal: a higher number means worse economy.
L/100 km = 235.2146 ÷ mpg (US) L/100 km = 282.4809 ÷ mpg (UK)
km/L = mpg × 0.4251437
Worked Example
Common Conversions
| From | Equals |
|---|---|
| 1 mpg | 235.2146 L/100 km |
| 1 L/100 km | 235.2146 mpg |
| 1 mpg | 0.4251437 km/L |
| 1 mpg (UK) | 0.8326742 mpg |
| 1 mpg (UK) | 282.4809 L/100 km |
| 1 mpg | 100 gal/100 mi |
Unit Definitions
| Unit | Equals | Exact? |
|---|---|---|
| Miles per US gallon (mpg) | 0.4251437074 km/L | Exact |
| Miles per UK gallon (mpg (UK)) | 0.3540061899 km/L | Exact |
| Kilometers per liter (km/L) | 1 km/L | Exact |
| Miles per liter (mi/L) | 1.609344 km/L | Exact |
| Liters per 100 km (L/100 km) | 100 ÷ km/L | Exact |
| US gallons per 100 miles (gal/100 mi) | (100 × 1.609344 ÷ 3.785411784) ÷ km/L | Exact |
Factors follow NIST Special Publication 811, Appendix B. "Exact" means the unit is defined as that value; results are rounded only for display.
Tips
Because L/100 km is a reciprocal, going from 10 to 20 mpg saves far more fuel than going from 30 to 40 mpg. UK mpg figures look about 20% better than US figures for the same car because the UK gallon is bigger.