Fuel Economy Converter
Convert MPG, km/L, and L/100 km fuel economy values.
This fuel economy converter switches between MPG (miles per gallon), km/L (kilometers per liter), and L/100km (liters per 100 kilometers) - the main fuel efficiency units used across different countries.
Enter a fuel economy value in any supported unit, and the calculator returns the equivalent in your chosen target unit.
Worked Calculation Examples
| Scenario | Result | Calculation Step |
|---|---|---|
| 30 MPG to L/100km | ≈7.84 L/100km | 235.214583 ÷ 30 ≈ 7.84 L/100km. |
| 6 L/100km to MPG | ≈39.2 MPG | 235.214583 ÷ 6 ≈ 39.2 MPG. |
Why MPG and L/100km Are Inversely Related
MPG and km/L measure distance per unit of fuel (higher is better), while L/100km measures fuel per unit of distance (lower is better) - this inverse relationship means the conversion between MPG and L/100km isn't a simple multiplication, but involves dividing a constant by the MPG value: L/100km = 235.214583 / MPG.
Why Fuel Economy Units Vary by Country
The US and UK commonly use MPG (though defined slightly differently between the two, due to different gallon sizes), while most of the rest of the world uses L/100km or km/L - comparing a vehicle's efficiency across markets often requires converting between these fundamentally different measurement conventions.
How to Use the Fuel Economy Converter
- Open the Fuel Economy Converter and enter the values requested in the input fields.
- Check the units, percentages, dates, or time periods before reading the answer.
- Review the instant result and adjust any value to compare another scenario.
- Use the formula, example, and FAQs below to understand how the fuel economy converter works.
Frequently Asked Questions
How do you convert MPG to L/100km?
Divide 235.214583 by the MPG value: L/100km = 235.214583 / MPG, since the two units measure efficiency in inverse directions (distance-per-fuel versus fuel-per-distance).
Is US MPG the same as UK MPG?
No - the US gallon and UK (imperial) gallon are different volumes, so a US MPG figure and a UK MPG figure for the same actual fuel efficiency will show different numbers, requiring a separate conversion factor between the two.
Why does lower L/100km mean better fuel economy?
L/100km measures how much fuel is consumed to travel a fixed distance, so a lower number means less fuel is needed for that distance - the opposite direction of MPG, where a higher number means better efficiency.
How do I use this fuel economy converter?
Enter the known values, review the units or settings, and the calculator updates the result instantly. The formula and example on this page show how the answer is produced.
What does the Fuel Economy Converter calculate?
Convert MPG, km/L, and L/100 km fuel economy values. It is designed for fast browser-based calculations without sign-up, downloads, or manual spreadsheet setup.
What formula does this fuel economy use?
The formula is: L/100km = 235.214583 / MPG. The inverse relationship in this conversion exists because MPG measures distance-per-fuel while L/100km measures fuel-per-distance - the EU and most of the world adopted L/100km as their standard fuel economy metric following the metric system's broader 20th-century adoption, while the US and UK retained MPG, a divergence that still complicates comparing vehicle efficiency ratings internationally today.
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Last updated: September 27, 2026.