Gas & Road Trip Cost Calculator
Estimate what a drive will cost in fuel and what each traveler owes.
Distance divided by MPG, times the price per gallon. Last reviewed October 4, 2026. Sources · Methodology
How trip fuel cost is calculated
Gallons = distance ÷ MPG · Cost = gallons × price per gallon
For a round trip the one-way distance is doubled. The cost per person is the total divided by the number of people sharing it.
Worked example: 300 miles each way at 28 MPG and $3.25 a gallon
- Round-trip distance: 600 miles
- Fuel needed: 21.4 gallons
- Total fuel cost: $69.64
- Split between 3 people: $23.21 each
- Cost per mile: $0.12
How fuel economy changes the cost
| Fuel economy | Gallons | Fuel cost |
|---|---|---|
| 20 MPG | 30 | $97.50 |
| 28 MPG | 21.4 | $69.64 |
| 35 MPG | 17.1 | $55.71 |
| 50 MPG | 12 | $39.00 |
Ways to use less fuel on a road trip
- Slow down. Fuel economy usually drops quickly above about 50 mph.
- Keep tires properly inflated and remove roof racks or cargo boxes you are not using.
- Use cruise control on flat highways to hold a steady speed.
- Avoid long idling.
What this estimate leaves out
- Tolls, parking and wear on the vehicle.
- Price differences between regions along your route.
- Detours, traffic and terrain, which change real-world MPG.
Frequently asked questions
How do I calculate the gas cost of a trip?
Divide the distance by your vehicle's miles per gallon to get gallons needed, then multiply by the price per gallon. A 300-mile drive at 30 MPG uses 10 gallons; at $3.50 a gallon that is $35.
Where do I find my car's MPG?
Check the trip computer, the window sticker, or look up your make and model on fueleconomy.gov. For the most accurate figure, divide miles driven by gallons added at your next fill-up.
Should I use city or highway MPG?
Use highway MPG for long road trips and combined MPG for mixed driving. Heavy loads, roof racks, high speeds and cold weather all reduce fuel economy.
How should we split gas money fairly?
The simplest method is to divide the total fuel cost equally among everyone in the car, including the driver. Some groups also give the driver a share for wear and tear.
Does this work for electric vehicles?
Not directly. For an EV, multiply the kilowatt-hours used per mile by the distance and your electricity price instead.
Sources
- U.S. Department of Energy and EPA: fueleconomy.gov
- U.S. Energy Information Administration: gasoline and diesel fuel update
Last reviewed October 4, 2026. Results are estimates; see our methodology and disclaimer.