Fuel Economy Unit Converter
Compare distance-per-volume and volume-per-distance fuel-economy conventions used across countries. US mpg uses the 3.785411784-liter US gallon, while imperial mpg uses the larger 4.54609-liter imperial gallon; this tool converts units only and does not predict a vehicle’s real efficiency or fuel cost.
Fuel Economy Unit Converter
Compare distance-per-volume and volume-per-distance fuel-economy conventions used across countries. US mpg uses the 3.785411784-liter US gallon, while imperial mpg uses the larger 4.54609-liter imperial gallon; this tool converts units only and does not predict a vehicle’s real efficiency or fuel cost.
Method and assumptions
Figur normalizes distance-per-volume units to km/L. For L/100 km it applies the reciprocal relationship 100 ÷ km/L. US mpg uses 1 US gal = 3.785411784 L and imperial mpg uses 1 imperial gal = 4.54609 L.
- The mile is the exact international mile of 1.609344 km.
- The entered value is positive; zero does not represent a convertible fuel economy and is rejected to avoid undefined division.
- Conversion changes the unit convention of a known efficiency; it does not estimate how a real vehicle will perform.
Unit conversion only. It does not include live fuel prices, trip costs, vehicle-specific predictions, or electric-vehicle energy economy.
Sources and references
Frequently asked questions
Why is L/100 km reciprocal?
MPG and km/L rise when efficiency improves, but L/100 km falls. Figur converts through km/L and uses 100 ÷ km/L when either side is L/100 km.
Are US mpg and imperial mpg the same?
No. Both use the same international mile, but an imperial gallon is larger than a US gallon, so the same physical fuel economy has a higher imperial-mpg number.