Fuel Efficiency Conversions

Convert fuel economy — MPG, L/100km, km/L. Free calculators for comparing cars across US and metric fuel labels.

5 units · 7 conversions

Fuel efficiency can be expressed as distance per volume (miles per gallon, km per liter) or volume per distance (liters per 100 km). US labels use MPG; Europe and Canada often use L/100km — and higher MPG is better while lower L/100km is better, which confuses direct comparison.

These units are reciprocal relationships, not simple multipliers. Our calculators apply standard conversion formulas so you can compare a 35 MPG US vehicle with a 6.7 L/100km European rating fairly.

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Real-world example

A rental car in Europe is listed at 5.5 L/100km and you want the US MPG equivalent. Converting gives roughly 43 MPG — useful when choosing the most economical option.

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Fuel Efficiency units explained

Miles per Gallon (US) (mpg) · base unit
Also: mpg, miles per gallon, us mpg
Miles per Gallon (Imperial) (mpg (Imp))
Also: imperial mpg, uk mpg
Liters per 100 Kilometers (L/100km)
Also: liters per 100km, l/100km
Kilometers per Liter (km/L)
Also: kilometers per liter, km/l
Miles per Liter (mi/L)
Also: miles per liter

Frequently asked questions

How do I convert MPG to L/100km?
Use the formula L/100km = 235.214583 / MPG (US). Example: 30 MPG ≈ 7.84 L/100km.
Why is lower L/100km better but higher MPG better?
L/100km measures fuel used per distance (lower is better). MPG measures distance per fuel (higher is better). They are inverse measures.

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