Fuel Cost Calculator
What a trip actually costs in gas.
Fuel needed:
Estimated cost:
How to use this calculator
Enter trip distance, your vehicle's MPG and the gas price, then press Calculate. Gallons needed and trip cost are shown.
What the result means
The cost is what that trip actually burns in fuel. Comparing vehicles on cost per mile reveals big differences over a year of driving.
How the calculation works
Fuel cost is distance divided by fuel economy, multiplied by the price per gallon. The tool uses your trip distance, your car's real MPG and the current local gas price - the same math as the old "divide miles by MPG" shortcut, done for you.
Worked example
A 400-mile road trip in a car that averages 28 MPG at $3.20 a gallon needs about 14.3 gallons and costs roughly $46. Cutting speed from 75 to 65 can push real-world MPG up enough to save 10-15% on that same trip.
Getting the inputs right
- Use real-world MPG, not the window sticker - highway numbers beat city, and loaded cars do worse.
- Use the price you actually pay; prices vary by state and by station within a few cents to a dollar.
- Separate trips - a daily commute at 30 mph costs different per mile than a freeway drive.
Beyond the tool
Once you know the fuel cost, compare it against maintenance, insurance and depreciation with the car ownership or cost-per-mile calculators to see a car's real running cost.
Frequently asked questions
How do I find my car's real MPG?
Divide miles driven by gallons used over a full tank — that's more accurate than the sticker.
Does this include wear and tear?
No — the IRS standard mileage rate (about 67c/mile in 2024) also covers depreciation and maintenance.
Does idling waste fuel?
Yes - roughly 0.2-0.5 gallons per hour idling, which the distance-based tool does not capture. Long waits are cheaper with the engine off.
Real-world fuel economy
Sticker MPG is rarely what you get. Track a few fill-ups (miles driven divided by gallons pumped) and use that number instead - it can be 10-25% worse in winter, in traffic, or with a loaded car. The tool's result is only as accurate as the MPG you enter, so use your measured figure for trips that matter.