MPG to L/100km Converter

Convert fuel economy between MPG (US), MPG (UK), km/L, and L/100 km with the gallon-size difference called out clearly.

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MPG to L/100km converter Convert US and UK mpg into litres per 100 kilometres and km/L instantly, with the gallon-size difference called out clearly.

Common presets

US and UK mpg are not interchangeable

A UK gallon is larger than a US gallon, so the same car always shows a higher mpg value in UK terms. If you are comparing reviews, labels, or owner reports, make sure you know which gallon the source used.

Quick checkpoints

30 mpg (US) is about 7.84 L/100km and 12.75 km/L. Lower L/100km is better, while higher mpg and km/L are better.

Enter a fuel economy figure Provide an mpg, km/L, or L/100km value to compare the four common efficiency units side by side.

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MPG to L/100km Converter

MPG to L/100km converter: US mpg, UK mpg, km/L, and metric consumption explained

An MPG to L/100km converter helps you move between the two most common ways of expressing vehicle fuel economy: miles per gallon and litres per 100 kilometres. It also keeps kilometres per litre in view so the same efficiency can be read as either fuel used over distance or distance gained from each litre.

Why MPG and L/100km are not mirror images by inspection

MPG and km/L rise as a vehicle becomes more efficient, but L/100km falls. That inverse relationship is why the conversion cannot be done by a simple one-to-one multiplier. The same car may look “better” in one system by showing a bigger number and “better” in another by showing a smaller number.

There is another complication: US mpg and UK mpg use different gallons. A UK gallon is larger than a US gallon, so any UK mpg figure for the same vehicle will always be higher than the US mpg figure.

L/100km = 235.215 / mpg (US)

Relationship between US mpg and metric consumption.

L/100km = 282.481 / mpg (UK)

Relationship between UK mpg and metric consumption.

L/100km = 100 / (km/L)

Metric consumption and metric efficiency are reciprocal forms.

When each unit is most useful

Use mpg when you are matching an American or British review, older brochure, or owner discussion that already quotes distance per gallon. Use L/100km when you are matching European labels, fleet reporting, or trip-cost calculations based on litres consumed over a fixed route length.

km/L is often the easiest “plain-language” metric efficiency format because it answers how far one litre takes you. It is especially useful when you want an intuitive comparison without the inverse logic of L/100km.

Why the same car can look different across sources

A car rated at 30 mpg (US) is about 36.03 mpg (UK), around 12.75 km/L, and about 7.84 L/100km. Those are all the same efficiency, just expressed in different systems.

That is why an international car review, dealer sheet, and owner forum may appear to disagree when they are actually describing the same performance using different gallon sizes and consumption formats.

Further reading

Frequently asked questions

Is lower L/100km better?

Yes. L/100km measures how much fuel the vehicle uses over a fixed distance, so a lower number means better efficiency.

 Why is UK mpg higher than US mpg?

Because the UK gallon is larger than the US gallon. The vehicle travels the same distance, but the gallon unit itself contains more fuel in UK terms.

 Why does km/L appear in this converter too?

Because many people prefer to read fuel economy as distance per litre rather than fuel used per 100 km. km/L and L/100km are both common metric expressions of the same efficiency.

 Can I compare international car specs directly after conversion?

Yes, as long as you account for the unit system. After converting to the same unit, you can make a like-for-like comparison more easily.

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