Gas Mileage Calculator
Divide miles driven by gallons used to get your true MPG — and see what each mile is costing you in fuel.
How it works
Fill the tank, drive, then fill it again and note the miles between the two stops. Divide those miles by the gallons it took to top off, and that's your MPG. Drive 310 miles on 11.2 gallons and you're getting about 27.7 MPG.
The trip-to-trip method is more accurate than a single tank because you're measuring a full tank's worth of fuel against the distance it actually carried you. Reset your trip odometer at the first fill-up to make the miles easy to read.
Adding the price per gallon turns MPG into a cost per mile, which is the number that really matters for budgeting a commute or a road trip.
Frequently asked questions
How do I calculate my MPG?
Fill up, drive, and fill up again. Take the miles you covered and divide by the gallons it took to refill. That ratio is your miles per gallon for that stretch of driving.
Why is my MPG different every time?
City versus highway, weather, tire pressure, cargo, and how hard you accelerate all move the number. Averaging several fill-ups gives a truer picture than any single tank.
What's a good MPG?
It depends on the vehicle. Many compact cars land in the 30s, mid-size sedans in the high 20s to low 30s, and trucks and SUVs often in the low 20s. Hybrids can top 45. Compare against your own car's history rather than a universal target.
How do I get cost per mile?
Multiply the gallons you used by the price per gallon to get the fill cost, then divide by the miles driven. Add the price in the calculator and it shows cost per mile automatically.