Value, From, To
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How this calculator works
Miles per gallon and kilometers per liter measure distance per unit of fuel, so higher is better. Liters per 100 km measures fuel per distance, so lower is better and the relationship with mpg is an inverse, not a simple multiplication. US and UK gallons differ, so the same car has a higher mpg figure in the UK.
Formula
- L/100 km = 235.214583 / mpg (US)
- L/100 km = 282.480936 / mpg (UK)
- km/L = 100 / (L/100 km)
- mpg (UK) = mpg (US) × 1.200950
Worked example
30 mpg (US) to L/100 km
- Value
- 30
- From
- Miles per US gallon (mpg (US))
- To
- Liters per 100 km (L/100 km)
Result7.8404861 L/100 km
30 mpg (US) = 7.8404861 L/100 km.
Frequently asked questions
How do I convert mpg to L/100 km?
Divide 235.215 by the US mpg figure. 30 mpg (US) is 7.84 L/100 km.
Why are UK mpg figures higher than US ones?
The imperial gallon is 4.546 L and the US gallon is 3.785 L. A larger gallon carries the car further, so the same car scores about 20% higher in UK mpg.
Is a lower L/100 km better?
Yes. It is the amount of fuel used to travel 100 km, so a smaller number means a more efficient car.
Sources
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Results are estimates based on the values you enter and the published method shown above. They do not replace professional medical, financial or legal advice. Method reviewed October 7, 2026. About this site