This fuel cost calculator estimates trip fuel spend from distance, efficiency, and fuel price fields on the page.
To measure vehicle efficiency first, use the gas mileage calculator. For distance checks, open the mileage calculator.
Fuel cost per mile: the number to keep
Fuel cost per mile = price per gallon ÷ MPG
At $3.40 a gallon and 31 MPG, fuel costs about 11.0¢ a mile. With that figure you can price any route by multiplying by distance. It is also what changes when you compare two cars or a rental. The $3.40 price is an example input, not a quoted market price.
Fuel cost calculator example: a 320-mile road trip, there and back
- Round-trip distance: 320 × 2 = 640 miles
- Fuel needed at 31 MPG: 640 ÷ 31 = 20.65 gallons
- Cost at $3.40/gal: 20.65 × 3.40 = $70.19
- Split four ways: $17.55 each
For a planning range, run the trip again with your MPG reduced by 10–15%. That covers highway speed, heavy luggage and air-conditioner use, all of which fueleconomy.gov lists as factors that reduce mileage. To check your average trip speed from distance and time, use the speed calculator.
Metric version: litres per 100 km
Cost = distance (km) × L/100 km ÷ 100 × price per litre
Example: 1,000 km at 6.5 L/100 km uses 65 L. At €1.80 per litre that is €117.00. To use the U.S.-unit fields instead, convert with MPG = 235.215 ÷ L/100 km. In this example, 6.5 L/100 km is about 36.2 MPG.
Where to find a realistic price per gallon
The U.S. Energy Information Administration publishes free weekly average retail prices for regular gasoline and diesel, nationally and by region. Use the regional figure for the area you will buy most of your fuel in. Prices on long routes can differ noticeably between regions.
Why the IRS mileage rate is so much higher than fuel cost
The IRS business standard mileage rate is 72.5¢ per mile for January 1–June 30, 2026 and 76¢ per mile from July 1, 2026. The Congressional Research Service explains that it covers all fixed and variable operating costs, including depreciation, insurance, tires and maintenance, not just fuel.
For the 640-mile trip, fuel was about $70, but the business rate gives 640 × $0.76 = $486.40 for miles driven after July 1. Use this calculator to budget fuel, and the IRS rate when you claim or reimburse business driving. Truck operators who need fuel plus payments, insurance and maintenance per mile can use the trucking cost per mile calculator.
Comparing two vehicles for the same trip
Fuel cost scales with the inverse of MPG, so small MPG gains matter most on thirsty vehicles. For the 640-mile trip at $3.40, a 22 MPG SUV burns 29.09 gallons ($98.91). A 31 MPG sedan burns 20.65 gallons ($70.19), and a 45 MPG hybrid burns 14.22 gallons ($48.36). Run the fuel cost calculator once per vehicle with the same price and distance so the comparison is like for like.
Electric and plug-in vehicles
For EVs, the same logic works per kWh: cost per mile = electricity price per kWh × kWh per mile. Public fast-charging is often priced well above home rates, so price the two separately.
Before a trip with the fuel cost calculator in hand, check that your tires are inflated to the pressure on the door label and remove roof boxes or heavy items you do not need. Both changes help real mileage and make the estimate more accurate.
If you share the cost with passengers, agree on the split before you leave. Keep receipts for each fill-up, then compare what you actually spent with the planned figure so your next estimate is closer.
For a long drive, add a small buffer to the budget for tolls, parking and food stops, since these are not part of fuel spend. A realistic total makes it easier to decide whether to drive, share the ride or take another way.
Last reviewed: October 2026