Fuel Economy Converter

The Fuel Economy Converter converts between U.S. miles per gallon (MPG), liters per 100 kilometers (L/100 km), and kilometers per liter (km/L). Because L/100 km is an inverse measure, the converter handles the non-linear relationship correctly rather than applying a simple multiplier.

Beginner⏱ 30 secondsUpdated 2026-07-05

Enter your details above and click “Convert Fuel Economy” to see your results here.

How This Tool Works

Enter a fuel economy figure, choose the unit you have and the unit you want, and read the converted result.

Formula & Method

Conversions pass through kilometers per liter as a common base. 1 US MPG ≈ 0.425144 km/L, and L/100 km = 100 ÷ km/L (an inverse relationship, so higher MPG means lower L/100 km).

Example Calculation

30 US MPG converts to about 7.84 L/100 km, or 12.75 km/L.

Please note: This calculator provides estimates for general informational purposes only. Results may not be accurate for every situation — use your judgment and consult a relevant professional when it matters.

Frequently Asked Questions

Does this use US or imperial MPG?+

This converter uses U.S. MPG (U.S. miles per U.S. gallon). A UK imperial gallon is larger, so imperial MPG figures are about 20% higher than U.S. MPG for the same car.

Why isn't L/100 km a simple multiple of MPG?+

L/100 km measures fuel used per distance, while MPG and km/L measure distance per fuel — they are inversely related, so the conversion divides rather than multiplies. That is why lower L/100 km and higher MPG both mean better efficiency.

How do I convert MPG to km/L?+

Multiply U.S. MPG by about 0.425144. For example, 30 MPG × 0.425144 ≈ 12.75 km/L.

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