Fuel Economy Converter
Convert between MPG (US), MPG (UK), km/L, and L/100km instantly.
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Popular conversions
About this fuel economy converter
This tool converts between 4 common fuel economy units used around the world. Pick any two units, enter a value, and the result updates instantly — every conversion happens directly in your browser, so there's no network request, no waiting, and it keeps working even if you lose your internet connection.
Higher isn't always better
For MPG (US), MPG (UK), and km/L, a higher number means better fuel efficiency. For L/100km, the standard used across the EU and most of the world, it's the opposite — a lower number means better efficiency, since it measures how much fuel gets consumed over a fixed distance rather than how far a fixed amount of fuel carries you.
Units covered
- Miles per US Gallon (MPG (US)) — the standard fuel economy figure on new-car window stickers and EPA ratings in the United States, using the smaller 3.785-liter US gallon.
- Miles per UK (Imperial) Gallon (MPG (UK)) — the figure used in the UK and Ireland, based on the larger 4.546-liter imperial gallon — the same car reports a higher MPG number in the US than in the UK purely because the gallons differ in size.
- Kilometers per Liter (km/L) — a metric distance-per-volume figure used in several countries, most notably Japan, as an alternative to the volume-per-distance L/100km standard used across most of Europe.
- Liters per 100 Kilometers (L/100km) — the standard fuel economy figure across the EU and most of the world — unlike the other three units here, a LOWER number means better efficiency, since it measures fuel consumed per fixed distance rather than distance per fixed fuel.
Frequently asked questions
Why does converting MPG to L/100km need a different kind of math?
MPG and km/L both measure distance covered per unit of fuel (higher is better), while L/100km measures fuel used per fixed distance (lower is better) — they're reciprocals of each other, not just different scale factors. This converter handles that reciprocal step automatically, but it's why a simple multiplication like the other unit converters on this site use wouldn't work here.
Why is US MPG different from UK MPG for the same car?
The US gallon (3.785 L) and the UK imperial gallon (4.546 L) are genuinely different volumes — about 20% apart. The same car with identical real-world fuel consumption reports a higher MPG figure in the UK than in the US purely because the UK gallon is larger, not because the car is more efficient.
What counts as "good" fuel economy?
It depends heavily on vehicle class and region, but as rough benchmarks: a typical modern gasoline sedan gets somewhere around 30-40 MPG (US) or roughly 6-8 L/100km, while larger SUVs and trucks often run 15-25 MPG (US) or roughly 9-16 L/100km. Hybrids and EVs shift these numbers substantially.
Does this work offline?
Yes — the conversion runs entirely in your browser with no network request needed.