Fuel Economy Converter

Convert fuel efficiency between miles per gallon (US and UK) and liters per 100 km - useful for comparing vehicles across regions that use different conventions.

Fuel Economy Converter

Live

Value

From

Converted value

8.40 L/100km

Note: lower L/100km is more efficient, while higher MPG is more efficient - the scales run in opposite directions.

The formula

L/100km = 235.21 / MPG (US) L/100km = 282.48 / MPG (UK)

Example

28 MPG (US) converts to about 8.40 L/100km. Remember: for MPG, higher is more efficient; for L/100km, lower is more efficient.

Step-by-step guide

Enter the value you want to convert.
Choose the "from" and "to" units - note that US and UK gallons are different sizes, so MPG (US) and MPG (UK) aren't interchangeable.
Read the converted result.

Common mistakes

Treating US and UK MPG as the same figure - a UK (imperial) gallon is larger than a US gallon, so the same real fuel efficiency gives a higher UK MPG number.

Assuming a linear conversion between MPG and L/100km - the relationship is inverse, not linear, since one measures distance per fuel and the other measures fuel per distance.

Frequently asked questions

Why is a UK gallon different from a US gallon?

They developed from different historical standards - a US gallon is about 3.79 liters, while a UK (imperial) gallon is about 4.55 liters, roughly 20% larger.

Which is more fuel efficient: higher MPG or lower L/100km?

Both indicate better efficiency, but in opposite directions - higher MPG is better, while lower L/100km is better, since one measures distance per fuel and the other measures fuel per distance.

Can I use this alongside the Gas Mileage Calculator?

Yes - calculate your actual MPG there from a fill-up, then convert it here to compare against a vehicle or spec sheet listed in L/100km.

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