Gas trip cost formula
Fuel cost = trip distance / MPG x gas price per gallon
For a 250-mile trip in a 30 MPG vehicle, the estimate is 250 / 30 = 8.33 gallons. At $3.50 per gallon, that trip costs about $29.17 in fuel.
Fuel estimate
Gas trip calculator
Calculate gas cost for a trip before you leave. Enter total road-trip distance, real-world MPG, gas price, and optional tolls to see gallons used, fuel cost, trip total, cost per mile, and a lower-to-higher fuel-price scenario.
What to enter
- Trip distance: enter total miles for the complete one-way or round trip you are budgeting.
- Vehicle MPG: use highway MPG for road trips or combined MPG for mixed driving.
- Gas price: the price per gallon you expect to pay.
- Tolls and fees: add the combined paid-road, bridge, tunnel, ferry, or express-lane amount for this route.
How to get a realistic fuel estimate
Manufacturer MPG and dashboard MPG are useful starting points, but real trips rarely match the sticker number exactly. Highway speed, stop-and-go traffic, wind, elevation, roof racks, cold weather, tire pressure, and extra passengers can all change the final number.
If you are planning a long drive, run two versions: one with your optimistic MPG and one with a lower MPG. The lower estimate gives you a safer fuel budget and helps compare gas cost against an EV trip or a different route.
Choose a current route price
The U.S. Energy Information Administration's July 13, 2026 data put regular gasoline at $3.855 nationally, but regional figures ranged from $3.423 on the Gulf Coast to $4.832 on the West Coast. A national average can be a poor input for a route that stays in one high- or low-price region.
Check the latest EIA regional update, then compare stations near planned stops. For a heavily loaded or mountainous trip, test a second result with MPG reduced by 10% to 15%. That range is a planning scenario, not a prediction of the vehicle's performance.
Related calculators
Gas trip cost FAQ
Should I use city MPG or highway MPG?
Use highway MPG for steady freeway driving, city MPG for stop-and-go routes, and combined MPG when the drive has both.
Does this include tolls and parking?
Yes. The calculator includes an optional tolls and route-fees field, then shows fuel cost and the combined trip total separately. Use the detailed gas-and-tolls page when charges vary by direction, vehicle class, or payment method.