Conversions
Fuel economy converter
Fuel economy is measured two ways. Miles per gallon counts distance per fuel, while liters per 100 km counts fuel per distance, so the scales run in opposite directions.
What this means
- That is 7.84 L/100 km, 30 US mpg, or 36.03 UK mpg.
- A UK gallon is larger than a US gallon, so the same car shows a higher mpg in the UK.
What if
About this calculator
What this calculator does
It converts any of four fuel economy units through kilometers per liter.
How it is calculated
km/L = mpg(US) * 1.609344 / 3.785411784
km/L = mpg(UK) * 1.609344 / 4.54609
L/100 km = 100 / (km/L)
How to read the result
Lower L/100 km is better. Higher mpg and km/L are better. Because one scale is inverted, equal mpg gains save less fuel at higher mpg.
Sources and method
Exact conversion factors from NIST where they are defined. Unit tests check round trips and known values.
Questions
What is 30 mpg in L/100 km?
About 7.84 L/100 km using US gallons.
Why is UK mpg higher?
A UK (imperial) gallon is 4.54609 liters, while a US gallon is 3.785411784 liters.
Is lower L/100 km better?
Yes. It means less fuel per 100 km.
Can I convert electric efficiency?
No. This page covers liquid fuel only.