How do I convert L/100km to mpg?

US mpg = 235.215 ÷ L/100km. UK mpg = 282.481 ÷ L/100km. The converter applies these for you. Remember that better economy means lower L/100km but higher mpg.

Kilometres per litre is the distance travelled on one litre of fuel. It is common in Japan and parts of Asia. To convert km/L to L/100km, divide 100 by the km/L value.

Why is my UK mpg higher than my US mpg for the same car?

Because the imperial gallon is about 20% larger than the US gallon. The same fuel use fills fewer US gallons, so the US mpg number is lower. Always check which gallon a figure uses before comparing cars across regions.

Is a lower or higher number better?

For L/100km, lower is better (less fuel per distance). For mpg and km/L, higher is better (more distance per fuel). The converter shows all four so you can compare on whichever scale you are used to, but keep the direction in mind.

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Fuel Economy Converter

Fuel economy is quoted in mutually incomprehensible units: continental Europe uses litres per 100 km, the United States uses miles per US gallon, the UK uses miles per imperial gallon, and Japan uses kilometres per litre. The same car looks thrifty or thirsty depending on which you read. This converter moves between all four so a foreign fuel-economy figure makes sense at a glance.

Enter the value you have and pick its unit. The converter returns the equivalent in L/100km, US mpg, UK mpg and km/L. Note that mpg is not symmetric with L/100km — a lower L/100km is better, while a higher mpg is better — so the converter handles the inversion for you.

It is the conversion that makes a foreign fuel-economy figure legible — the continental “5 L/100km” and the American “47 mpg” are the same car, and this tool says so in one line instead of a head-scratching unit juggle.

Value

From

Enter your values to see the result.

How this is calculated

Every input is first reduced to litres per 100 km, the common currency. A direct L/100km value passes through; US mpg is converted with L/100km = 235.215 ÷ mpg; UK (imperial) mpg with L/100km = 282.481 ÷ mpg; and km/L with L/100km = 100 ÷ km/L. From that single L/100km value, all other units are derived by inverting the same constants.

The two mpg figures differ because the gallons differ: a US gallon is 3.785 litres and an imperial gallon is 4.546 litres, so the same fuel use gives a higher mpg number in the UK than in the US. The constants 235.215 and 282.481 embed those gallon sizes and the mile-to-kilometre conversion. Note that mpg and L/100km are inversely related — better economy means higher mpg but lower L/100km — so the converter handles the inversion rather than requiring you to reason about it.

The conversion is exact for the units themselves, but real-world fuel economy varies with driving style, load, terrain, weather and vehicle condition, so a quoted figure is a benchmark rather than a guarantee. Manufacturer figures are produced under standardised test cycles that often flatter real-world economy, especially for hybrids and plug-in vehicles. Use the converter to compare like with like across regions, then expect your actual economy to differ.

Worked example

A European car is rated at 5.0 L/100km. You want the US mpg equivalent.

1L/100km = 5.0 (already in the base unit).
2US mpg = 235.215 ÷ 5.0 = 47.0 mpg.
3UK mpg = 282.481 ÷ 5.0 = 56.5 mpg.
4km/L = 100 ÷ 5.0 = 20.0 km/L.
5So 5.0 L/100km ≈ 47 US mpg ≈ 56.5 UK mpg ≈ 20 km/L.

Frequently asked questions

Why are US and UK mpg different?: Because the gallons differ. A US gallon is 3.785 litres and an imperial gallon is 4.546 litres, so the same fuel use gives a higher mpg number in the UK than in the US. Always check which gallon a figure uses before comparing.
How do I convert L/100km to mpg?: US mpg = 235.215 ÷ L/100km. UK mpg = 282.481 ÷ L/100km. The converter applies these for you. Remember that better economy means lower L/100km but higher mpg.
What is km/L?: Kilometres per litre is the distance travelled on one litre of fuel. It is common in Japan and parts of Asia. To convert km/L to L/100km, divide 100 by the km/L value.
Why is my UK mpg higher than my US mpg for the same car?: Because the imperial gallon is about 20% larger than the US gallon. The same fuel use fills fewer US gallons, so the US mpg number is lower. Always check which gallon a figure uses before comparing cars across regions.
Is a lower or higher number better?: For L/100km, lower is better (less fuel per distance). For mpg and km/L, higher is better (more distance per fuel). The converter shows all four so you can compare on whichever scale you are used to, but keep the direction in mind.

Related calculators

Method: exact conversion through L/100km using US gallon (3.785411784 L) and imperial gallon (4.54609 L) with 1 mile = 1.609344 km. Last updated: September 2026.

These results are general estimates from established formulas and conversion factors. Paint coverage, tile yields, concrete volumes, fuel economy, oven behaviour and clothing and shoe sizes vary by product, surface, vehicle, oven and brand. Always confirm with your supplier, the product label or the brand’s own size chart before buying or acting on a calculation.