Fuel Economy Converter
Convert MPG, km/L and L/100km instantly.
How to use
- 1 Enter your fuel economy value.
- 2 Select the unit your value is currently in.
- 3 Read the equivalent figure in all four units below.
- 4 Copy the full conversion with one click.
About Fuel Economy Converter
The Fuel Economy Converter turns any fuel-efficiency figure into the four units drivers actually use around the world: miles per US gallon, miles per Imperial (UK) gallon, kilometres per litre and litres per 100 kilometres.
These units trip people up because a US gallon and a UK gallon are different sizes, and because L/100km runs on an inverse scale — a lower number means a more efficient car, the opposite of MPG.
This tool handles all of that for you.
Type a value, pick the unit it is written in, and every other unit updates at once using exact NIST conversion constants (1 mile = 1.609344 km, 1 US gallon = 3.785411784 L, 1 UK gallon = 4.54609 L).
That makes it ideal for comparing a car advertised at "45 MPG" in a British review against a model rated in L/100km on a European spec sheet, or for working out the real-world economy of an American import.
Everything is computed locally in your browser, so nothing you type is uploaded or stored, and the converter keeps working offline once loaded.
Results are rounded to two decimal places for readability while staying accurate enough for everyday comparisons and quick mental sanity-checks.
FAQ
Why is MPG (UK) always higher than MPG (US)?
An Imperial (UK) gallon is about 20% larger than a US gallon, so the same car travels further per gallon — giving a higher MPG number for the identical real-world efficiency.
Why does a lower L/100km mean a more efficient car?
L/100km measures consumption, not distance, so it is the inverse of MPG. Fewer litres burned over 100km means the vehicle uses less fuel and is therefore more efficient.