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Free online fuel economy converter

Fuel efficiency is measured differently around the world — MPG in the US and UK, L/100km in Europe, and km/L in Asia. This converter shows all five common units at once.

About this calculator

How to use

  1. Enter a fuel economy value.
  2. Select the unit you are converting from.
  3. Select the unit you want to convert to.
  4. The result and a full conversion table appear instantly.
  5. Click “Share with my numbers” to copy a URL with your inputs.

Conversion formulas

All conversions use L/100km as the internal reference:

FromTo L/100km
MPG (US)235.215 ÷ mpg
MPG (UK)282.481 ÷ mpg_uk
km/L100 ÷ kml
L/100km(no change)
L/100mivalue × 100 ÷ 160.934

Worked example

30 MPG (US) converted:

  • L/100km = 235.215 ÷ 30 = 7.84 L/100km
  • MPG (UK) = 282.481 ÷ 7.84 = 36.03 MPG UK
  • km/L = 100 ÷ 7.84 = 12.76 km/L

Notes

  • Constants: 1 US gallon = 3.785411784 L; 1 UK gallon = 4.54609 L; 1 mile = 1.609344 km.
  • Source: US EPA fuel economy methodology; Wikipedia “Fuel efficiency” (https://en.wikipedia.org/wiki/Fuel_efficiency).
  • L/100km and L/100mi use an inverse relationship to distance — lower is more efficient.

Frequently asked

How do you convert MPG to L/100km?
Divide 235.21 by the MPG value. Example: 30 MPG = 235.21 ÷ 30 ≈ 7.84 L/100km.
How do US MPG and UK MPG differ?
The UK gallon (imperial gallon) is larger than the US gallon — 4.546 L vs 3.785 L. So 1 UK MPG ≈ 1.2009 US MPG. A car rated 40 MPG UK is about 33 MPG US.
Is a higher or lower L/100km better?
Lower is better for L/100km and L/100mi — they measure how much fuel you use per distance. Higher is better for MPG and km/L — they measure how far you go per unit of fuel.
What is km/L?
Kilometers per liter (km/L) is used in Japan, India, and some other countries. It is mathematically equivalent to MPG but using metric units. 1 km/L ≈ 2.352 US MPG.
What is the formula for L/100km to MPG?
MPG = 235.215 ÷ L/100km. Example: 8 L/100km = 235.215 ÷ 8 ≈ 29.4 MPG (US).