Fuel Economy Converter
Enter a fuel economy figure and choose its unit to see it in all the others. Useful when comparing cars across countries or reading a foreign review.
Convert fuel economy
Why this is not a simple multiplication
Miles per gallon and km per liter measure distance per unit of fuel, so higher is better. Liters per 100 km measures fuel per distance, so lower is better. Because one is the reciprocal of the other, converting between them means dividing into a constant rather than multiplying by a factor.
Formulas
L/100 km = 235.214583 ÷ mpg (US)
L/100 km = 282.480936 ÷ mpg (UK)
km/L = mpg (US) × 0.425143707
mpg (UK) = mpg (US) × 1.200950
Worked example
30 mpg (US) in L/100 km
- km/L = 30 × 1.609344 ÷ 3.785411784 = 12.754
- L/100 km = 100 ÷ 12.754 = 7.84
30 mpg (US) ≈ 7.84 L/100 km.
Quick reference
| mpg | L/100 km (from US mpg) | L/100 km (from UK mpg) | km/L (from US mpg) |
|---|---|---|---|
| 10 | 23.5 | 28.2 | 4.25 |
| 15 | 15.7 | 18.8 | 6.38 |
| 20 | 11.8 | 14.1 | 8.5 |
| 25 | 9.41 | 11.3 | 10.6 |
| 30 | 7.84 | 9.42 | 12.8 |
| 35 | 6.72 | 8.07 | 14.9 |
| 40 | 5.88 | 7.06 | 17 |
| 50 | 4.7 | 5.65 | 21.3 |
| 60 | 3.92 | 4.71 | 25.5 |
US or UK gallons?
UK mpg figures look about 20% better than US mpg figures for the same car, because the imperial gallon is larger (4.546 L vs 3.785 L). Always check which gallon a review or specification uses before comparing.