Fuel Economy Converter
Convert between MPG (US/UK), km/L and L/100km fuel efficiency units.
Fuel economy is the rare unit family where conversions aren't just scaled — they're inverted. MPG and km/L measure distance per fuel (bigger is better), while L/100km measures fuel per distance (smaller is better). On top of that, a UK gallon is 20% larger than a US gallon, so "40 MPG" means different things on each side of the Atlantic.
This converter handles all four conventions — US MPG, UK (imperial) MPG, km/L and L/100km — including the reciprocal math between efficiency and consumption units. Use it to compare car reviews across regions, translate a rental car's dashboard reading, or convert manufacturer specs for a fuel-cost estimate.
How to use Fuel Economy Converter
- 1
Enter the fuel economy value
Type the figure from the spec sheet or dashboard.
- 2
Choose the source unit
US MPG, UK MPG, km/L or L/100km.
- 3
Choose the target unit
The converted figure appears instantly.
Features
- Handles the inverse relationship between MPG and L/100km correctly
- Distinguishes US and UK (imperial) gallons
- Instant, precise conversion
Frequently asked questions
Common mistakes to avoid
- Comparing US and UK MPG figures directly without adjusting for gallon size.
- Averaging L/100km values by simple arithmetic mean across different distances — consumption must be distance-weighted.
Get new tools in your inbox
One email a month with new tools, guides, and updates. No spam, unsubscribe anytime.