Enter a value
Type any fuel economy number — from a car's window sticker, a spec sheet or a road-trip calculation.
Fuel Economy Converter
Enter a fuel economy value and instantly see it converted between MPG (US), MPG (UK), litres per 100km and kilometres per litre.
MPG (US)—
MPG (UK)—
L/100km—
km/L—
How it works
Pick its unit
Choose whether the value you entered is MPG (US), MPG (UK), L/100km or km/L.
Read every conversion
All four units update instantly using exact gallon and mile definitions — no rounding shortcuts.
FAQ
Why are US and UK MPG different?
A US gallon (3.785 litres) is smaller than a UK/Imperial gallon (4.546 litres), so the same fuel efficiency produces a higher MPG number in the UK than in the US, even for an identical car.
Why does a lower L/100km mean better fuel economy?
L/100km measures how much fuel is consumed over a fixed distance, so a smaller number means less fuel is needed — the opposite direction from MPG, where a bigger number is better.
How accurate are these conversions?
The formulas use exact unit definitions (1 US gallon = 3.785411784 L, 1 UK gallon = 4.54609 L, 1 mile = 1.609344 km), so results are mathematically precise. Real-world fuel economy still varies with driving conditions.