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MPG to L per 100km converter icon showing a car

MPG to L/100km Converter

MPG to L/100km Converter

Convert fuel economy between MPG, L/100km and km/L

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MPG and L/100km are inversely related. MPG measures distance per unit of fuel (more is better), while L/100km measures fuel used per fixed distance (less is better). A car that gets better fuel economy has a HIGHER MPG but a LOWER L/100km — they move in opposite directions.

US and Imperial (UK) gallons are different sizes. A US gallon is 3.785411784 liters, while an Imperial gallon is 4.54609 liters — about 20% larger. The same car will show a higher number in Imperial MPG than in US MPG, even though fuel economy hasn't changed.

Example: 30 US MPG ≈ 7.84 L/100km ≈ 12.76 km/L ≈ 36.03 Imperial MPG.

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MPG and L/100km are inversely related — higher MPG means lower L/100km. Free tool by calculator24x7.com.

MPG and L/100km aren’t just different units, they measure fuel economy in opposite directions, a higher MPG is better, while a lower L/100km is better. This converter switches between them along with km/L and Imperial MPG.

How to use this MPG to L/100km converter

  1. Enter a value and select your From unit (US MPG, Imperial MPG, L/100km, or km/L).
  2. Select your To unit.
  3. Read the converted result instantly, or tap Swap Units to reverse the direction.

What this converter does

MPG measures distance per unit of fuel (more is better), while L/100km measures fuel used per fixed distance (less is better). A car that gets better fuel economy has a HIGHER MPG but a LOWER L/100km, they move in opposite directions, which is why this isn’t a simple linear conversion but an inverse relationship.

L/100km = 235.215 ÷ US MPG (approximate, based on US gallon and km conversion factors)
Example: 30 US MPG ≈ 7.84 L/100km ≈ 12.76 km/L ≈ 36.03 Imperial MPG

Why US and Imperial MPG give different numbers for the same car

US and Imperial (UK) gallons are different sizes, a US gallon is 3.785411784 liters, while an Imperial gallon is 4.54609 liters, about 20% larger. The same car will show a higher number in Imperial MPG than in US MPG, even though its actual fuel economy hasn’t changed at all, purely because the “gallon” being measured is a different size.

Frequently asked questions

Why does higher MPG mean better fuel economy but lower L/100km also mean better?

MPG measures how far you go per unit of fuel (more distance is better), while L/100km measures how much fuel you use over a fixed distance (less fuel is better), they’re inverse measurements of the same underlying efficiency, so they move in opposite directions.

Why does the same car show different MPG figures in the US vs UK?

A US gallon (3.785 L) is about 20% smaller than an Imperial/UK gallon (4.546 L), so a car’s fuel economy expressed in Imperial MPG will always show a higher number than the same car’s US MPG, even though nothing about the car’s actual efficiency has changed.