Fuel Cost & MPG Calculator
See what your car really burns and what it costs to drive. Enter your numbers and get instant results, no sign-up, free.
Enter miles and gallons to see your results.
How to calculate your MPG
The most accurate method is measuring tank to tank. Fill up all the way, reset your trip meter, drive normally, and at the next fill-up write down how many gallons you added and how many miles you covered. Then the formula is simple:
MPG = miles / gallons
Example: you added 11 gallons after driving 320 miles. 320 / 11 = 29 MPG. That is your real-world fuel economy, not the EPA sticker number that gets measured under idealized conditions.
How much does it cost to drive per mile
Cost per mile is the price per gallon divided by your MPG. At 29 MPG and $3.50 a gallon that works out to about $0.12 per mile. Multiply that by your yearly mileage to see what fuel really costs you over a year, a number that often surprises buyers shopping for a car.
Why real MPG differs from the sticker
Fuel economy depends on driving style, route (city vs highway), season, tire pressure and how healthy the car is. A clogged air filter, worn spark plugs or underinflated tires can raise fuel use by double digits. If a car burns far more than it should, that is a signal to check it, and we cover it in our guides on spark plugs and ignition coils and tire pressure and TPMS.
Fuel economy when buying a used car
When you buy a used car, real fuel cost is one of the bigger running costs alongside insurance and service. A diesel pays off on high mileage, gas suits city driving, hybrid and electric change the math again. We break it down in gas, diesel, hybrid or electric. Before you commit to a specific car, check its history and condition with the MotoPPI app, so you catch the faults that push fuel use and repair bills up. See also the true cost of owning a used car and how to inspect a used car.
Frequently asked questions
How do I calculate my MPG?
Divide the miles you drove by the gallons you put in. The most accurate way is tank to tank: fill up, reset the trip meter, drive, then fill up again and do the math.
How much does it cost to drive per mile?
Price per gallon divided by your MPG. At 30 MPG and $3.50 a gallon that is about $0.12 per mile.
Is the EPA MPG rating accurate?
Rarely exact. It is measured in standardized test conditions. Real-world MPG is usually 10 to 30 percent lower depending on how and where you drive.