Fuel Economy Converter
Convert between mpg and L/100km — the world's two fuel-economy systems.
Convert fuel economy between miles per gallon (US) and liters per 100 km — the two systems the world actually uses. Remember: with mpg, higher is better; with L/100km, lower is better.
How it's calculated
The two scales are inverses linked by a constant: L/100km = 235.214583 ÷ mpg, and mpg = 235.214583 ÷ (L/100km). Note the scales run in opposite directions — efficient cars have high mpg and low L/100km.
Frequently asked questions
What is 30 mpg in L/100km?
About 7.84 L/100km. Enter 30, choose mpg → L/100km — the formula is 235.214583 ÷ 30.
Are mpg and L/100km proportional?
No — they run in opposite directions. High mpg means efficient; high L/100km means thirsty. Both describe the same car, just from different angles.
US or imperial gallons?
Yes — US and imperial gallons differ (1 imperial gallon = 1.20095 US gallons). This converter uses US gallons, the standard for American mpg figures.