Fuel economy converter
Switch instantly between miles per gallon (US and UK), liters per 100 km and kilometers per liter. And if you want the real number, calculate your actual gas mileage from your last fill-up.
Enter a value to see all the equivalents.
Calculate your real-world gas mileage
MPG vs. L/100 km: the scales run in opposite directions
In the US and UK fuel economy is quoted in miles per gallon: the higher the number, the better. Most of Europe uses liters per 100 km, which works the other way around — lower is better — and converts as 235.2 divided by the US MPG figure, so 30 MPG is about 7.8 L/100 km. There is one extra trap: a US gallon is 3.785 liters while a British imperial gallon is 4.546 liters, which means 40 MPG in a UK magazine is a noticeably better result than 40 MPG on an American window sticker. This converter handles both gallons, plus kilometers per liter, so you can compare any spec sheet at a glance.
How to measure your car's true fuel economy
The fill-up method is the most reliable: fill the tank completely, reset your trip odometer, drive normally, and at the next fill-up write down the miles driven and the gallons it takes to top the tank back off. Miles divided by gallons is your real MPG — often lower than the EPA rating and even the dashboard trip computer, which tends to be optimistic. Repeat the measurement over two or three tanks for a solid average: traffic, weather, and tire pressure can swing the result by 15–20%.