Fuel Economy Converter
Enter a fuel economy value and its unit to see the equivalent in liters per 100km, km per liter, US MPG, and UK MPG.
How fuel economy conversion works
L/100km and MPG measure fuel economy in opposite directions — L/100km is fuel used per fixed distance (lower is better), while MPG is distance traveled per fixed fuel amount (higher is better). This inverse relationship is why the formulas involve division rather than a simple multiplication factor.
US and UK (imperial) gallons are different sizes — a US gallon is about 3.785 liters, while a UK gallon is about 4.546 liters — so the same car gets a different MPG number depending on which gallon definition is used, even though its actual fuel consumption hasn't changed.
Frequently asked questions
Why is a US MPG number different from a UK MPG number for the same car?
Because the US and UK define "gallon" differently — a UK (imperial) gallon is about 20% larger than a US gallon, so the same real-world fuel economy produces a higher MPG figure when expressed in UK gallons.
How do I convert L/100km to km/L?
Divide 100 by the L/100km value: km/L = 100 / (L/100km). For example, 8 L/100km is 100/8 = 12.5 km/L.
Why does a lower L/100km mean better fuel economy, while a higher MPG does?
L/100km measures fuel consumed over a fixed distance, so using less fuel (a lower number) is more efficient; MPG measures distance covered per unit of fuel, so covering more distance (a higher number) is more efficient.