Gas Mileage Calculator
Enter the distance you drove and the fuel used to calculate your miles per gallon (MPG), then add a fuel price to estimate the cost of any trip distance at that mileage.
How the Gas Mileage formula works
Fuel efficiency and trip cost:
MPG = Distance driven / Gallons used Cost per mile = Price per gallon / MPG Trip cost = Cost per mile × Trip distance
Step-by-step calculation
- Divide the distance driven by the gallons of fuel used to get MPG.
- Divide the price per gallon by MPG to find the cost per mile.
- Multiply the cost per mile by any trip distance to estimate that trip's fuel cost.
Worked example
A car that drives 320 miles on 10 gallons gets 32 MPG. At $3.50/gallon, that's about $0.11 per mile — so a 150-mile road trip would cost roughly $16.40 in fuel.
Frequently asked questions
Why does my real-world MPG differ from the sticker rating?
EPA sticker estimates are measured under standardized test conditions. Real-world driving — highway vs. city, terrain, load, driving style, and weather — routinely shifts actual MPG several miles per gallon in either direction.
How can I get a more accurate MPG reading?
Fill your tank completely, reset your trip odometer, drive normally until the next fill-up, then divide the miles driven by the gallons needed to refill — repeating this over a few tanks gives a more reliable average than a single reading.