Gas Mileage Calculator
Work out your fuel economy in MPG or litres per 100 km from distance and fuel used.
Runs in your browser — nothing is sent or saved.
How to work out gas mileage
- Pick miles and gallons, or kilometres and litres.
- Type the distance you drove.
- Type the fuel you used to drive it.
- See your fuel economy as MPG and as litres per 100 km.
What gas mileage means
Gas mileage is how far you go on a set amount of fuel. Fill up, drive, then note the distance and the fuel it took to refill, and this gives you miles per gallon or litres per 100 km. The tool shows both numbers at once, so you can compare with a figure in either unit.
MPG and L/100km side by side
The two units run in opposite directions: a higher MPG is better, a lower L/100km is better. Here is how they line up.
| Miles per gallon | Litres per 100 km |
|---|---|
| 20 | 11.8 |
| 25 | 9.4 |
| 30 | 7.8 |
| 35 | 6.7 |
| 40 | 5.9 |
| 50 | 4.7 |
Get a true reading
For an honest result, fill the tank to the same point both times and measure over a decent distance, not one short trip. A single tank of mixed city and highway driving gives a fair everyday figure for your fuel economy.
FAQ
How do I calculate miles per gallon?
Divide the miles driven by the gallons used. This mpg calculator does it for you and also shows the litres per 100 km reading.
What is a good gas mileage?
It depends on the vehicle, but many cars sit around 25 to 40 MPG, which is about 9 to 6 L/100km. Smaller and hybrid cars do better.
How do I convert MPG to L/100km?
Divide 235.215 by the MPG figure. For 30 MPG that is about 7.8 L/100km. The table above lists common values.
Should I measure over one trip?
No. Use at least a full tank over mixed driving. One short trip gives a reading that is too high or too low to trust.
Are my numbers private?
Yes. The gas mileage is worked out in your browser and nothing is saved.