Gas Trip Cost Calculator
This gas cost calculator uses your car’s official EPA gas mileage and this week’s gas price in your state to show what your drive will cost, per trip and per person. I built it because most trip calculators make you guess both numbers, and a wrong guess on mileage can throw the answer off by a lot.
Gas prices: EIA weekly averages, Sept. 21, 2026 · Gas mileage: U.S. EPA (FuelEconomy.gov) · By Nathan Brooks
Trip cost calculator
Get the miles from your map app. Tip: Dallas to Houston is about 240 miles.
Your car’s gas mileage
Or type your MPG below.
Gas price
Estimates only. Real mileage depends on speed, load, weather, traffic and your car’s condition. State prices are weekly averages; nine states use their own EIA average and the rest use their region’s average.
How the trip cost is calculated
The formula is simple: miles ÷ miles per gallon × price per gallon. Our calculator does the same math, but fills in the two numbers people usually get wrong:
- Your car’s official gas mileage from the U.S. Environmental Protection Agency (EPA), for cars from 1990 on.
- This week’s gas price in your state, from the U.S. Energy Information Administration (EIA).
What a road trip costs at this week’s prices
| Round trip | 25 mpg | 30 mpg | 40 mpg |
|---|---|---|---|
| 100 miles | $17.92 | $14.93 | $11.20 |
| 300 miles | $53.76 | $44.80 | $33.60 |
| 500 miles | $89.60 | $74.67 | $56.00 |
| 1,000 miles | $179.20 | $149.33 | $112.00 |
Example using $4.48 a gallon, the U.S. average for regular in late September 2026 (EIA).
What this year’s prices mean for holiday trips
Here’s a quick example. A 500-mile round trip in a car that gets 28 mpg uses about 18 gallons. At $4.33, the U.S. average in the week of Oct. 12, 2026, that’s about $77 in gas. At last year’s $3.06, the same trip cost about $55. So this year’s Thanksgiving drive will likely cost around $20 more for a typical family car, before any price changes between now and then.
That’s not a reason to cancel a trip, but it’s a good reason to price it now and split it fairly if you’re carpooling. The per-person cost is the number I’d share with whoever’s riding along. — Nathan Brooks
How to spend less on gas on a road trip
- Drive at a steady speed. FuelEconomy.gov notes that gas mileage usually drops quickly above 50 mph. Every extra 5 mph over 50 is like paying more for each gallon. On a long trip, cruise control and a slightly lower speed are the cheapest upgrade you can make.
- Check tire pressure before you leave. Underinflated tires waste gas and wear out faster, and it takes five minutes at most stations.
- Pack light and skip the roof box if you don’t need it. Extra weight and wind drag cost mileage for every mile of the trip.
- Fill up in the cheaper state. If you’re crossing into a state with lower prices, wait until after the border; if it’s the other way around, fill up before. See gas prices by state.
- Avoid highway-exit stations when you can and use a gas rewards program. On a trip with two or three fill-ups, a few cents a gallon adds up.
Quick answers
How do I calculate gas cost for a trip?
Divide the miles by your car’s MPG to get gallons, then multiply by the price per gallon. Example: 300 miles ÷ 30 mpg = 10 gallons × $4.48 = $44.80.
Where does the MPG come from?
When you pick a car, we load its official EPA ratings from FuelEconomy.gov, a U.S. government site. You can also type your own MPG, for example from your car’s trip computer.
Should I use city, highway or combined MPG?
For road trips, highway MPG is usually closest. For daily driving in town, use city. If you’re not sure, use combined.
How do I split gas money with friends?
Enter the number of people sharing the cost. The calculator divides the total evenly and shows the cost per person.
Keep saving
Sources
FuelEconomy.gov web services (U.S. DOE/EPA) · FuelEconomy.gov: driving more efficiently · EIA Gasoline and Diesel Fuel Update
FuelPriceScout is an independent information site. We don’t sell fuel and we’re not affiliated with any gas station, retailer or rewards program mentioned here. Prices are averages from public sources and are not what a specific station charges; program terms can change, so always check the official site before you sign up. How we get our data.