Fuel Economy Converter
Convert fuel economy between miles per gallon (US and UK), kilometers per liter, and liters per 100 km, handling the inverse relationship correctly. Calculates in your browser.
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About fuel economy conversions
Enter a value and choose the units to convert between. Each fuel economy unit is defined against a single base unit, so any pair lines up consistently, the table shows your value in every fuel economy unit at once.
L/100 km is inverse to the others: lower is better. It is 100 ÷ (km/L), so a higher km/L means a lower L/100 km.
What this does
A fuel economy converter changes a vehicle’s efficiency between miles per gallon (US and UK), kilometers per liter, and liters per 100 km, handling the inverse relationship correctly.
How to use it
- Enter a value and pick its unit.
- Choose the unit to convert to.
- Read the converted result instantly.
- Mind whether the mpg figure is US or UK.
How it works
L/100 km measures fuel used per distance, so lower is better, the reciprocal of mpg and km/L. US and UK gallons differ (3.785 L vs 4.546 L), so the same car reads higher in UK mpg.
L/100 km = 100 ÷ (km/L)
Example
30 US mpg is about 7.84 L/100 km, and roughly 36 UK mpg. A car at 5 L/100 km does 20 km per liter.
Sources & methodology
Last updated .
Frequently asked questions
Why is L/100 km handled differently?
It measures fuel used per distance, so lower is better, the opposite of mpg and km/L. It is the reciprocal: 100 ÷ (km/L) = L/100 km.
Are US and UK mpg the same?
No. A UK gallon is larger (4.546 L vs 3.785 L), so the same car shows a higher number in UK mpg.
Is my data stored?
No. Everything is calculated locally in your browser.
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