How to use the MPG Calculator
Enter the distance driven and fuel used and the result appears straight away. Everything runs in your browser, so nothing you type is uploaded.
The formula
US: mpg = miles ÷ gallons. Metric: L/100 km = litres ÷ km × 100
Examples
- 350 miles on 12.5 gallons
28 mpg (US) 8.4 L/100 km 11.9 km per litre
- 420 miles on 14 gallons
30 mpg (US) 7.84 L/100 km 12.75 km per litre
- 180 miles on 9 gallons
20 mpg (US) 11.76 L/100 km 8.5 km per litre
Limitations and assumptions
US gallons in US mode, litres in metric mode. Fill the tank to the same level each time for accuracy.
Frequently asked questions
How do I calculate MPG?
Miles driven ÷ gallons used.
Why is my real MPG different from the sticker?
Speed, load, weather, tyre pressure and driving style all change it.
What is a good MPG?
It depends on vehicle class; many modern petrol cars fall between about 25 and 40.
How do I convert to L/100 km?
Divide 235.215 by the MPG figure (US gallons).