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Fuel economy converter
MPG (UK or US), L/100km, and km/L, converted all at once.
—MPG (UK)
—MPG (US)
—L / 100km
—km / litre
How it works
Everything converts through km/L as a common base: MPG (UK) uses a 4.54609-litre gallon, MPG (US) uses a 3.78541-litre gallon, both over 1.60934 km per mile, and L/100km is just the reciprocal of km/L scaled to 100km.
FAQ
- Why are UK and US MPG different numbers for the same car?
- A UK (imperial) gallon is about 4.546 litres, while a US gallon is about 3.785 litres — the same fuel efficiency gives a higher MPG figure in the UK/imperial measure simply because the gallon itself is bigger.
- Why does L/100km go down as efficiency improves, unlike MPG?
- L/100km measures fuel used over a fixed distance, so a more efficient car uses less fuel and the number drops — MPG measures distance over a fixed amount of fuel, so a more efficient car goes further and the number rises. They're inversely related.
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