Fuel Economy Converter
Convert fuel economy between US MPG, UK MPG, km/L, and L/100km.
How it works
Fuel economy is measured two opposite ways, which is where the confusion starts. Miles per gallon and kilometers per liter go up when a car is more efficient, while liters per 100 km goes down.
Because of that flip, L/100km is an inverse relationship: it equals 235.2 divided by US MPG. The tool handles that quietly so you do not have to remember which way the math runs.
It also keeps US and UK gallons straight, since a UK gallon is about 20 percent larger — a detail that quietly inflates British MPG figures compared with American ones.
Frequently asked questions
Why does L/100km go down when the car is more efficient?
Because it measures fuel used per distance, not distance per fuel. Less fuel to cover the same 100 km means a lower, better number — the opposite of MPG.
Is a US gallon the same as a UK gallon?
No. A UK gallon is roughly 4.55 liters versus 3.79 for a US gallon, so the same car scores higher MPG in UK figures. The tool keeps them separate.
How do I convert MPG to L/100km?
Divide 235.2 by the US MPG figure. For example, 30 US MPG is about 7.8 L/100km. The converter does this instantly.