Fuel Economy Converter
Convert between miles per gallon, kilometres per litre and litres per 100 km.
Processing: This tool runs entirely in your browser. Your input and any file you open stay on your device — nothing is uploaded to a server.
How to use the fuel economy converter
- Type the amount you want to convert.
- Choose the unit you have and the unit you want.
- Read the result, or use the table showing all 5 units at once.
About this tool
Fuel economy is measured two opposite ways. Miles per gallon and kilometres per litre are distance per fuel, where higher is better. Litres per 100 km is fuel per distance, where lower is better — so converting between them inverts the number rather than scaling it.
The other trap is the gallon. Imperial MPG figures are about 20% higher than US MPG for the same car, because an imperial gallon is larger. A car listed at 40 mpg in the UK is about 33 mpg in the US, with no difference in the vehicle.
Common uses
- Comparing a European car's L/100km against US MPG.
- Checking a UK MPG figure against a US one.
- Converting a trip computer reading.
Frequently asked questions
- Why is imperial MPG higher than US MPG?
- An imperial gallon is 4.546 litres against the US gallon's 3.785, so the same car travels further on one imperial gallon. The figure is about 20% higher.
- Why does the number invert for L/100km?
- Because it measures fuel per distance rather than distance per fuel. Better economy means a smaller number, so the conversion is a reciprocal.
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