⛽ Fuel Economy Converter
Enter fuel economy in km/L (kilometers per liter, common in Japan and elsewhere) to convert it to L/100km (used in Europe), US mpg, and UK mpg. Handy for comparing fuel economy figures across regions.
How to use
- Enter the fuel economy in km/L (kilometers traveled per liter of fuel).
- The equivalent values in L/100km, US mpg, and UK mpg are calculated automatically.
How the calculation works
This tool converts fuel economy in km/L (kilometres per litre) into three other measures. L/100km (litres used per 100 km), used in Europe and elsewhere, is 100 divided by km/L. L/100km = 100 ÷ km/L mpg (miles per gallon) is used in the US and UK. The conversion uses the exact definitions 1 mile = 1.609344 km, 1 US gallon = 3.785411784 L, and 1 UK (imperial) gallon = 4.54609 L. mpg (US) = km/L × 3.785411784 ÷ 1.609344 ≈ km/L × 2.352 mpg (UK) = km/L × 4.54609 ÷ 1.609344 ≈ km/L × 2.825 Note that higher km/L and mpg figures mean better economy, while for L/100km a lower figure is better.
Worked example
15 km/L L/100km: 100 ÷ 15 ≈ 6.67 mpg (US): 15 × 2.352 ≈ 35.28 mpg (UK): 15 × 2.825 ≈ 42.37 20 km/L L/100km: 5.00 mpg (US): 47.04 mpg (UK): 56.50 A US brochure listing "30 mpg" means 30 ÷ 2.352 ≈ 12.75 km/L.
Things to be aware of
- Test procedures differ by country and era (Japan's WLTC mode, the US EPA, Europe's WLTP). Even in the same units, official figures are not always directly comparable.
- L/100km is best for comparing fuel costs, because differences translate directly into fuel used.
- Electric vehicle efficiency (km/kWh, Wh/km and so on) is not covered.
FAQ
How does L/100km relate to km/L?
L/100km measures how much fuel is needed to travel 100km — it's the inverse of km/L (L/100km = 100 ÷ km/L). A lower number means better fuel economy.
Why are US mpg and UK mpg different for the same fuel economy?
The US gallon (about 3.785 liters) and the UK (imperial) gallon (about 4.546 liters) are defined differently, so the same fuel economy yields a higher UK mpg figure than US mpg.
What conversion factors does this use?
This uses the exact defined constants: 1 mile = 1.609344 km, 1 US gallon = 3.785411784 L, and 1 UK (imperial) gallon = 4.54609 L.