This converter changes fuel economy between miles per gallon (MPG) and litres per 100 km (L/100km), in both directions, with a choice of UK or US gallons. The two measures run in opposite senses — higher MPG is better, lower L/100km is better — so the tool also helps compare figures across regions.
How it works
The conversion combines three exact factors: 1 mile = 1.609344 km, 1 UK gallon = 4.54609 L, and 1 US gallon = 3.785411784 L. With the chosen gallon size in litres (G):
- L/100km = (G × 100) ÷ (MPG × 1.609344)
- MPG = (G × 100) ÷ (L per 100km × 1.609344)
The two quantities are reciprocal once scaled by the unit factors, which is why an efficient car has high MPG but low L/100km. Pick the gallon type before reading the result, since UK and US gallons give different answers for the same MPG.
Example
A car rated at 50 US MPG in L/100km:
(3.785412 × 100) ÷ (50 × 1.609344) = 4.70 L/100km.
| MPG (US) | L/100km |
|---|---|
| 30 | 7.84 |
| 40 | 5.88 |
| 50 | 4.70 |
| 60 | 3.92 |
The conversion runs entirely in your browser, so nothing is uploaded.