DIY Cost Tools
Fuel Economy Converter
CONVERSION CALCULATOR
Convert fuel economy between US miles per gallon, imperial miles per gallon, kilometers per liter, and liters per 100 kilometers.
How it works
Distance-per-volume units increase as efficiency improves, while liters per 100 kilometers decrease. The calculator converts through L/100 km so it can handle this inverse relationship.
Conversion formulas
L/100 km = 235.214583 ÷ US mpg
L/100 km = 282.480936 ÷ imperial mpg
L/100 km = 100 ÷ km/L
Worked example
30 US mpg equals approximately 7.84049 liters per 100 kilometers.
Important limits
- US and imperial gallons are different sizes.
- Real-world economy varies with speed, weather, load, terrain, maintenance, and driving style.
- This converts fuel economy values; it does not estimate trip fuel cost.
Frequently asked questions
Why is the formula divided instead of multiplied?
MPG measures distance per fuel, while L/100 km measures fuel per distance, so the relationship is inverse.
Which is better, a high or low result?
Higher mpg or km/L is better; lower L/100 km is better.
Review notes
Constants use exact international mile and liter relationships with US and imperial gallons. Last reviewed September 30, 2026.