How to calculate gas cost for a trip
To calculate the gas cost of a trip, divide the distance by your car's miles per gallon to get gallons, then multiply by the price per gallon. That is all a fuel cost calculator does; the work is in using honest inputs.
- Distance: use the route length from your map app, and double it for a round trip.
- MPG: use the highway figure for long trips and the combined figure for mixed driving. If you have measured your own mileage with the MPG calculator, use that.
- Price: prices differ by more than a dollar a gallon between regions. The calculator uses the EIA weekly average for the area you pick, or your own price.[1]
| Trip | 20 mpg | 28 mpg | 35 mpg | 50 mpg |
|---|---|---|---|---|
| Commute week (100 mi) | $19.98 | $14.27 | $11.41 | $7.99 |
| Weekend trip (300 mi) | $59.93 | $42.80 | $34.24 | $23.97 |
| Long road trip (1,000 mi) | $200 | $143 | $114 | $80 |
| A year of driving (12,000 mi) | $2,397 | $1,712 | $1,370 | $959 |
Gas prices by region this week
The same trip costs very different amounts depending on where you fill up. In the week of November 9, 2026, regular gasoline averaged $5.11 in West Coast and $3.48 in Gulf Coast, according to the U.S. Energy Information Administration's weekly survey of retail stations.[1] The EIA attributes regional differences to state and local taxes, distance from supply, supply disruptions, retail competition and operating costs.[3] The full weekly table is published by area.[2] The average cost of gas page has the full weekly table and the trend, and gas in California explains why that state is usually the most expensive.
| Area | Regular, $/gal | Trip cost |
|---|---|---|
| U.S. | $3.995 | $71.34 |
| East Coast | $3.847 | $68.70 |
| New England | $4.060 | $72.50 |
| Central Atlantic | $4.146 | $74.04 |
| Lower Atlantic | $3.609 | $64.45 |
| Midwest | $3.868 | $69.07 |
| Gulf Coast | $3.481 | $62.16 |
| Rocky Mountain | $3.946 | $70.46 |
| West Coast | $5.110 | $91.25 |
| West Coast less California | $4.584 | $81.86 |
Fuel cost calculator for a year of driving
For a yearly fuel budget, use the miles you drive in a year instead of a trip. At 12,000 miles and 28 mpg you buy 429 gallons, about $1,712 at this week's U.S. price. The EPA fuel economy label does the same arithmetic for its "annual fuel cost", using 15,000 miles a year, 55% city and 45% highway driving and a fixed fuel price.[4] The average new vehicle of model year 2024 gets 27.2 mpg in the EPA's real-world estimate.[6]
Splitting gas money and mileage reimbursement
To split gas money fairly, divide the fuel cost by the number of people. The example trip costs $71.34, or $23.78 each for three riders. Gas is not the whole cost of a mile, though: wear, tires and depreciation add more. That is why the IRS business mileage rate is 76 cents a mile from July 1, 2026 (72.5 cents for January to June), several times the fuel cost per mile of a typical car.[7]
Getting better mileage on a road tripFueleconomy.gov notes that gas mileage usually decreases rapidly at speeds above 50 mph, and that roof-top cargo boxes and extra weight both cost fuel.[5]
Common mistakes
- Using the wrong rating. The fuel economy label gives separate city, highway and combined figures; match the one to the trip.[4]
- Forgetting the return leg. Choose "Round trip" if you are coming back.
- Using last month's price. Prices change weekly; the calculator's default is this week's EIA average.
To see fuel next to insurance, depreciation and the rest, use the cost of owning a car calculator.
Frequently asked questions
How do I calculate the gas cost of a trip?
Gallons = miles ÷ MPG; cost = gallons × price. 500 miles at 28 mpg is 17.9 gallons; at $4.00 that is $71.34.
How much does it cost to drive 100 miles?
At $4.00 a gallon: $15.98 at 25 mpg, $11.41 at 35 mpg and $7.99 at 50 mpg.
Where do the gas prices come from?
From the U.S. Energy Information Administration's weekly survey of retail gasoline prices, released Mondays; this page uses the week of November 9, 2026.[1]
Is a fuel cost calculator accurate for diesel or premium?
Yes, if you enter the price you pay. The area averages are for regular gasoline; type your diesel or premium price in "your own price".
Sources
- Gasoline and Diesel Fuel Update (weekly retail prices)
- Weekly retail gasoline and diesel prices (all areas)
- Gasoline explained: regional gasoline price differences
- Learn More About the Fuel Economy Label for Gasoline Vehicles
- Driving More Efficiently
- Highlights of the Automotive Trends Report (2025 edition)
- Standard mileage rates (Notice 2026-10; Announcement 2026-11)