Liters per 100 Kilometers to Miles per Gallon (UK) Converter | L/100km to mpg (UK)

What this converter does

Across most of Europe, fuel economy is quoted in litres per 100 kilometres, but in the UK people think in miles per Imperial gallon. This converter takes an L/100km figure and gives you UK mpg. Enter the L/100km value and read off the mpg, so a continental economy figure makes sense in British terms.

The rule and its constant

The conversion is a division, since the two measures run in opposite directions:

mpg (UK) = 282.481 ÷ L/100km

That constant, 282.481, carries both the unit change and the reciprocal in one move, and it is built on the UK gallon of about 4.546 litres. So the answer is in UK mpg, which reads higher than US mpg for the same L/100km. Divide 282.481 by the L/100km figure and you have it.

Why a small L/100km gives a big mpg

Expect the flip as you convert. A low L/100km figure marks a frugal car, and it turns into a high UK mpg. A high L/100km figure, a thirsty car, turns into a low mpg. So a small L/100km number coming back as a large mpg is simply the measure turning over: little fuel for the distance is the same as plenty of distance for the fuel. The lower the L/100km, the higher the mpg.

A worked example

Say a European car is rated at 6 L/100km and you want that in UK mpg.

• 282.481 ÷ 6 = 47.1 mpg (UK)

So 6 L/100km is about 47.1 UK mpg. That same 6 L/100km would be roughly 39 mpg in US terms, and the gap is purely the gallon. In UK terms, this is a comfortably economical car.

Common L/100km values in mpg (UK)

As anchors, a frugal 5 L/100km is about 56.5 mpg UK, while a thirsty 12 L/100km is under 24 mpg UK.

Where you would use it

This is for a UK mpg thinker reading a continental spec. European car listings give economy in L/100km, so converting lets you weigh them against the UK mpg figures you know. It helps when looking at a model sold across Europe, when a review quotes L/100km, or when an imported car arrives with metric figures. Just keep in mind the answer is Imperial-gallon mpg, which is why it reads higher than the US equivalent of the same L/100km.

Questions people ask

How do I convert L/100km to UK mpg?

Divide 282.481 by the L/100km figure. The conversion is a division because the two measures run in opposite directions.

Is the result in UK or US mpg?

UK mpg, based on the Imperial gallon. The same L/100km figure gives a lower number in US mpg.

What is 6 L/100km in UK mpg?

About 47.1 mpg, a comfortably economical figure in Imperial-gallon terms.

References

1. National Institute of Standards and Technology (NIST), Special Publication 811, Guide for the Use of the International System of Units (gallon definitions and unit conversions). https://www.nist.gov/pml/special-publication-811