Everyday
Gas Mileage Calculator
Find your car's real fuel economy from the distance you drove and the fuel it used. Get MPG (US & UK), L/100 km and km/L all at once — enter a trip distance or your odometer readings, and add the fuel price to see your cost per mile.
Use odometer readings
Price per gallon of fuel
Fuel economy
30.0 MPG
MPG (US)
30.0
MPG (UK)
36.0
L / 100 km
7.84
km / L
12.75
Cost per mile$0.12
How to measure your gas mileage
1
Fill the tank and reset your trip meter (or note the odometer reading).
2
Drive as normal, then fill up again and note how much fuel it took and how far you went.
3
Enter the numbers here — distance and fuel — and read your economy in every unit.
The formula
MPG = miles ÷ gallons
L/100 km = litres ÷ km × 100
Example. 300 miles on 10 US gallons is 30 MPG — the same as about 7.8 L/100 km or 12.8 km/L. At $3.50 a gallon, that trip costs roughly 12 cents a mile.
Frequently asked questions
Fill the tank, note the distance you travel (the trip meter is easiest), then at the next fill-up note how much fuel it took to top up. Divide the distance by the fuel used. The calculator does the division and converts it into MPG, L per 100km and km per litre.