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Fuel Economy Converter

Convert fuel economy between L/100 km, km/L, US MPG and UK MPG, with the inverse maths handled for you.

  • 8L/100 km
  • 12.5km/L
  • 29.402MPG (US)
  • 35.31MPG (UK)

L/100 km is inverse: lower is more efficient, while higher MPG or km/L is more efficient.

How to use it

  1. Enter a value Your fuel economy figure.
  2. Choose its unit L/100 km, km/L, US MPG or UK MPG.
  3. Read every unit All four equivalents are shown at once.

Examples

8 L/100 km ~29.4 US MPG
30 US MPG ~7.84 L/100 km

About this tool

Fuel economy is quoted differently around the world: litres per 100 km in much of Europe, miles per gallon in the US and UK, and kilometres per litre elsewhere. This converter translates between all four so you can compare cars on equal terms.

The tricky part is that L/100 km is an inverse measure — fewer litres per distance is better, whereas a higher MPG is better — so a straight multiplication won’t do. This tool handles the inversion correctly, and even distinguishes US from UK gallons. It all runs in your browser.

Frequently asked questions

Why isn't this a simple conversion?

L/100 km measures fuel per distance, while MPG and km/L measure distance per fuel — they're inverses. Converting between them isn't a single multiplier, which this tool handles correctly.

What's the difference between US and UK MPG?

The gallons differ — a UK (imperial) gallon is larger than a US gallon — so the same car has a higher MPG figure in UK units.

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Updated June 13, 2026