Fuel Consumption Converter
Convert between miles per gallon, litres per 100 km, kilometres per litre and miles per litre. Handles both the US and UK gallon and shows cost per distance for a given fuel price.
Pair it with the Speed Converter for journey maths, or Power if you are comparing engine output.
How to use the Fuel Converter
- 1 Enter the fuel consumption figure.
- 2 Choose the unit you are converting from — miles per gallon (US or UK), litres per 100 km, or kilometres per litre.
- 3 Read the equivalent in the other units.
- 4 Swap direction to convert the other way.
How It Works
Some units measure distance per unit of fuel (higher is better) while others measure fuel per unit of distance (lower is better). The converter treats these as reciprocals so the numbers stay meaningful in both directions.
- mpg (US) and mpg (UK)
- Litres per 100 km and km per litre
- Miles per litre
- Fuel cost per 100 km / 100 miles
- Full comparison table
Frequently asked questions
Why is there no simple multiplier between mpg and litres per 100 km?
Because they are inversely related. MPG measures distance per unit of fuel, L/100 km measures fuel per unit of distance, so the conversion is 235.215 ÷ mpg (for US gallons). Doubling your mpg halves your L/100 km, which no single multiplication can express.
Why does the UK mpg differ from the US mpg?
Because the gallons differ. A UK gallon is 4.546 litres against the US 3.785 litres, so the same real consumption reads about 20% higher in UK mpg. Always check which gallon a figure uses before comparing vehicles across countries.
Which figure should I use to compare cars?
Whichever you like, as long as you are consistent — but be aware that mpg flatters efficient cars and compresses the differences at the top end. L/100 km is linear, so a drop from 4 to 3 is the same saving as 10 to 9, whereas in mpg those look very different.
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