How cost per mile is worked out
Cost per mile = price per gallon ÷ MPG
A car that gets 25 MPG burns one gallon every 25 miles, so each mile uses a 25th of a gallon. At this week’s U.S. average of $4.284, that’s $4.284 ÷ 25 = 17.1¢ a mile, or $17.14 for every 100 miles. Drive 1,000 miles a month and fuel comes to about $171 a month and $2,056 a year.
Gas cost per mile by MPG
At the U.S. average regular gas price of $4.284 a gallon, from EIA for the week of October 19, 2026.
| Fuel economy | Per mile | Per 100 miles | Per 1,000 miles |
|---|---|---|---|
| 15 MPG | 28.6¢ | $28.56 | $286 |
| 20 MPG | 21.4¢ | $21.42 | $214 |
| 25 MPG | 17.1¢ | $17.14 | $171 |
| 30 MPG | 14.3¢ | $14.28 | $143 |
| 35 MPG | 12.2¢ | $12.24 | $122 |
| 40 MPG | 10.7¢ | $10.71 | $107 |
| 50 MPG | 8.6¢ | $8.57 | $86 |
The gap shrinks as MPG climbs. Going from 15 to 20 MPG saves 7.1¢ a mile, while going from 40 to 50 MPG saves only 2.1¢. That’s why trading a thirsty truck for an average car saves far more than trading an average car for a hybrid.
Cost per mile by region
The same 25 MPG car costs a different amount to run depending on where you fill up.
| Region | Gas price | Per mile at 25 MPG |
|---|---|---|
| New England | $4.249 | 17.0¢ |
| Central Atlantic | $4.312 | 17.2¢ |
| Lower Atlantic | $3.860 | 15.4¢ |
| Midwest | $4.145 | 16.6¢ |
| Gulf Coast | $3.784 | 15.1¢ |
| Rocky Mountain | $4.468 | 17.9¢ |
| West Coast (excluding California) | $5.007 | 20.0¢ |
| California | $6.031 | 24.1¢ |
Weekly retail prices from the U.S. Energy Information Administration, updated every week.
Gas is only part of what a mile costs
AAA’s 2026 driving cost study puts maintenance, repairs and tires at about 11.7¢ a mile for a new car, and the loss in value at about $4,422 a year over 15,000 miles, roughly 29.5¢ a mile. Add a 25 MPG car’s gas and the total is close to 58.3¢ a mile, before insurance, registration and loan interest.
That’s why the IRS business mileage rate, 76.0¢ a mile from July 2026, is several times the cost of gas alone. To see the full cost of a particular trip, use the rent or drive calculator; for reimbursement, use the mileage reimbursement calculator.
Common questions
Is it cheaper per mile to drive a diesel?
Diesel usually costs more per gallon, but diesel engines often go further on each gallon. Divide the diesel price by the diesel vehicle’s MPG and compare it with the gas model’s figure; the calculator works the same way for both.
Why is my real cost per mile higher than the calculator says?
Real fuel economy drops with short trips, city traffic, high speeds, cold weather, heavy loads and idling. If you fill up to the brim twice and divide the miles between fill-ups by the gallons you added, you get your actual MPG to use here.
How can I lower my gas cost per mile?
Drive steadily, keep highway speeds moderate, keep tires at the pressure on the door sticker and take off roof racks you aren’t using. Filling up where prices are lower helps too: compare the regional table above.
Related calculators
- Road trip gas calculator: the fuel cost of one trip, split between riders.
- RV and towing fuel calculator: motorhomes and trucks pulling a trailer.
- Moving truck gas calculator: fuel for a rental truck by size.