Fuel Economy Converter
Convert fuel economy between mpg, litres per 100km and km per litre instantly with this free converter that works in your browser.
Enter Values
Before you rely on this: First-pass guide only. Verify safety-critical or regulated work against the relevant standards, your project requirements and a qualified professional.
How to use this calculator
- Enter fuel use in L/100km.
- Press Calculate.
How it works
Converts between litres per 100 km, miles per gallon (US) and kilometres per litre. Note L/100km is inverse — a lower number is better.
Worked example
10 L/100km. = 10 km/L ≈ 23.5 mpg.
Common mistakes
- Mixing US and UK MPG — a UK gallon is bigger, so UK MPG reads higher.
- Treating L/100km and MPG as proportional — they're inverse.
Frequently asked questions
L/100km vs MPG?
They're inverse measures — lower L/100km is better, while higher MPG is better.
Why do US and UK MPG differ?
A UK gallon is ~4.546 L vs ~3.785 L in the US, so the same car shows a higher UK MPG.
Why is L/100km 'inverse' to MPG?
With L/100km a lower number is better economy, but with MPG a higher number is better — they move in opposite directions, so don't compare them directly.
Is MPG here US or UK?
This shows US MPG. A UK (imperial) gallon is larger, so UK MPG figures are about 20% higher for the same real economy.
Related tools
Explore more in Units, Measurement & Converters.
Cite this tool
Zerdly. (2026). Fuel Economy Converter. Retrieved from https://www.zerdly.com/tools/fuel-economy-converter/
Tip: Enter any known values to calculate the remaining results.
Designed to run locally in your browser. Tool inputs are not intentionally stored by Zerdly unless stated otherwise.