FUEL ECONOMY
MPG calculator
Enter the miles you drove and the litres used to calculate real-world UK MPG, plus useful fuel economy conversions.
REAL-WORLD ECONOMY
Calculate your MPG
HOW IT WORKS
Calculate real MPG from fuel actually used
The most useful MPG figure is usually your own real-world result rather than the number shown on a brochure. Fill the tank, record your mileage, then record how many litres it takes to refill. Enter those two figures above and the calculator converts the fuel used into UK miles per imperial gallon.
UK MPG and US MPG are not the same because the gallons are different sizes. One imperial gallon contains 4.54609 litres, while one US gallon contains 3.78541 litres. This page uses UK MPG as the main figure and shows the US equivalent separately.
What is a good MPG?
There is no single good MPG for every vehicle. Size, engine type, weight, speed, temperature and journey type all matter. A small petrol hatchback and a large diesel SUV should not be judged against the same number. Tracking your own MPG over time is more useful for spotting a change in efficiency.
MPG and litres per 100km
Lower L/100km is better, while higher MPG is better. The calculator shows both so you can compare UK figures with European fuel-consumption figures without doing the conversion yourself.
QUESTIONS ANSWERED
Frequently asked questions
How do I calculate MPG in the UK?
Divide miles driven by litres used, then multiply by 4.54609 to convert litres into an imperial gallon.
Why is UK MPG different from US MPG?
The UK uses the imperial gallon, which is larger than the US gallon. The same journey therefore produces a higher numerical MPG figure in UK units.
Is 40 MPG good?
It can be reasonable for many petrol cars, but vehicle type and driving conditions matter. Compare it with your own vehicle’s normal real-world economy.
Can I use this for diesel and petrol cars?
Yes. MPG is a measure of distance per gallon, so the calculation works for petrol and diesel vehicles.
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