How do I convert miles per gallon (mpg) to litres per 100 kilometres (L/100km)?

Divide 282.48 by the mpg value to get L/100km. For example, 35 mpg equals 282.48 ÷ 35 = 8.07 L/100km. Note that this uses US gallons. For UK mpg (imperial gallons), divide 282.48 × 1.20095 = 339.15 by the mpg value instead. A fuel-efficient car rated at 50 mpg (US) equals 4.70 L/100km — considered excellent by European standards.

Why does a lower L/100km number mean better fuel economy?

Litres per 100 km is an inverse efficiency scale — it measures consumption rather than range. A lower number means the car uses less fuel to travel 100 km, so lower is better. Miles per gallon works the opposite way: higher is better, since it measures how far you can travel on a fixed amount of fuel. This inversion is why the two scales cannot be converted with simple multiplication — you must use division, as shown in the formula above.

Fuel Consumption Conversions

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Popular Comparisons

	L/100km	mpg (US)	mpg (UK)	km/L
Hybrid car	4.5	52.3	62.8	22.2
Average car	8	29.4	35.3	12.5
SUV	12	19.6	23.5	8.3
Sports car	15	15.7	18.8	6.7
Large truck	25	9.4	11.3	4.0

Fuel Consumption

Fuel consumption measures the relationship between the distance a vehicle travels and the amount of fuel it uses. Two fundamentally different approaches exist: efficiency (how far you can go on a fixed amount of fuel) and consumption (how much fuel you need to travel a fixed distance). Miles per gallon (mpg), used in the United States and United Kingdom, measures efficiency — higher is better. Litres per 100 kilometres (L/100km), standard throughout Europe, Asia, and Australia, measures consumption — lower is better. This directional inversion means the two scales cannot be converted by simple multiplication; the relationship is: L/100km = 235.21 ÷ mpg (US) or 282.48 ÷ mpg (UK).

The difference between US and UK miles per gallon arises from the different sizes of their gallons. A US gallon equals 3.785 litres, while a UK (imperial) gallon equals 4.546 litres — making the UK gallon approximately 20% larger. A car with identical fuel consumption will therefore appear to achieve higher mpg figures on the UK scale than the US scale. When comparing fuel economy across international car reviews and specifications, it is essential to confirm which gallon system is being used.

Kilometres per litre (km/L), common in India, Japan, and parts of Latin America, is the metric equivalent of miles per gallon — again measuring efficiency with higher being better. The conversion between km/L and L/100km follows the same inverse relationship: km/L = 100 ÷ L/100km. As automotive markets globalise and electric vehicles introduce new energy efficiency metrics such as kWh per 100 km, understanding fuel consumption unit conversion becomes increasingly relevant for consumers, engineers, and policy-makers worldwide.

Fuel Consumption conversions

List of Fuel Consumption conversions
‣ miles per UK gallon (mpg (imp)) to miles per gallon (mpg)
‣ liters per 100 kilometers (L/100 km) to miles per gallon (mpg)
‣ kilometers per liter (km/L) to miles per gallon (mpg)

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