Gas Mileage (MPG) Calculator
Calculate your car's real fuel economy from a fill-up — miles per gallon, L/100 km and km/L — and the fuel cost per mile or km.
How to use
- 1Fill the tank, reset the trip meter, then drive normally.
- 2At the next fill-up, enter the distance driven, the fuel added and the price.
How it's calculated
MPG = miles ÷ gallons. L/100 km = litres ÷ km × 100. Cost per mile = total cost ÷ miles.
Frequently asked questions
Why fill the tank completely?
The fuel you add after a full tank equals the fuel you used — the 'tank-to-tank' method is the simplest accurate test.
Why is my MPG lower than the EPA figure?
Short trips, cold weather, high speeds, aggressive acceleration and air conditioning all reduce real-world economy.
How do I convert MPG to L/100 km?
L/100 km = 235.21 ÷ MPG (US). 30 MPG ≈ 7.84 L/100 km.