Use this fuel cost calculator to estimate how much gas a road trip or daily commute will cost. Enter the distance, your car’s MPG and the gas price, and it shows the total cost, cost per person, gallons needed, and a monthly commute estimate.
- Cost per person $0
- Gallons needed 0
- Fill-ups (approx.) 0
- Cost per mile $0
- Monthly commute fuel $0
Real-world MPG changes with speed, traffic, weather, AC use and load.
How to Calculate Gas Cost for a Trip
The formula is simple: fuel cost = distance ÷ MPG × price per gallon. For example, a 250-mile trip in a car that gets 28 MPG uses about 8.9 gallons. At $3.50 a gallon, that is about $31.25 one way, or about $62.50 round trip.
Finding Your Real MPG
- Official ratings: check your car’s EPA city, highway and combined MPG on fueleconomy.gov or the window sticker.
- Your car’s trip computer: shows average MPG, though it can be slightly optimistic.
- Measure it yourself: fill the tank, reset the trip meter, drive, refill, and divide miles driven by gallons added.
What Changes Your Fuel Cost
- Speed: fuel economy usually drops noticeably above about 50–60 mph.
- Driving style: fast acceleration and hard braking waste fuel.
- Air conditioning: fueleconomy.gov notes AC use can reduce fuel economy by more than 25% in very hot conditions, especially on short trips.
- Weight and roof racks: extra weight and roof boxes reduce MPG.
- Tire pressure: underinflated tires increase rolling resistance.
- Traffic and terrain: stop-and-go driving and hills use more fuel.
Ways to Spend Less on Gas
- Drive at steady, moderate speeds and use cruise control on highways.
- Keep tires inflated to the pressure on the door-jamb sticker.
- Remove unused roof racks and heavy cargo.
- Combine errands into one trip.
- Compare gas prices with an app and use store or credit card fuel rewards.
Related guides: find out whether car AC uses gas, calculate your total cost of ownership, and compare EV charging costs.
Fuel Cost Calculator FAQ
How Do I Calculate Gas Cost for a Trip?
Divide the trip distance by your car’s MPG to get gallons, then multiply by the price per gallon.
How Much Gas Will a 500-Mile Trip Use?
It depends on MPG. At 25 MPG, it uses about 20 gallons; at 35 MPG, about 14.3 gallons.
Should I Use City or Highway MPG?
Use highway MPG for road trips and combined or city MPG for daily driving in town.
How Do I Split Gas Money on a Road Trip?
Divide the total fuel cost by the number of people sharing it. The calculator shows the cost per person.
Does Driving Faster Use More Gas?
Yes. Fuel economy generally drops at higher speeds because of increased aerodynamic drag.
What Is Cost per Mile for Gas?
Divide the price per gallon by your MPG. At $3.50 a gallon and 28 MPG, fuel costs about 12.5 cents per mile.