Fuel Cost Calculator
Enter your trip distance, your vehicle's fuel economy and the current price per gallon to estimate the total fuel cost.
Fuel cost for a trip equals the gallons you will use times the price per gallon, where gallons used is the trip distance divided by your miles per gallon. A 300-mile trip in a car that gets 25 mpg uses 12 gallons; at $3.50 per gallon that is $42.00. Cost per mile is the total divided by the distance.
How to Use This Calculator
Enter three numbers: the trip distance in miles, your vehicle's fuel economy in miles per gallon, and the current price per gallon. The calculator returns the total fuel cost, the number of gallons you will burn, and your cost per mile. For a round trip, either double the distance or run the tool twice.
For the most accurate result, use your real-world MPG rather than the EPA sticker figure — highway trips usually beat the sticker while city and towing fall short. Many trip computers show a lifetime or recent average MPG you can enter directly. Update the price per gallon to whatever you are actually paying locally, since fuel prices vary widely by region and over time.
How the Calculation Works
The math is two short steps. First, gallons used = distance ÷ MPG, because MPG tells you how many miles each gallon carries you. Second, fuel cost = gallons × price per gallon. Cost per mile is just the total cost divided by the distance, a handy figure for comparing vehicles or deciding whether a trip is worth driving versus other options.
Worked Example
Suppose you are driving 300 miles in a car that averages 25 mpg, and gas is $3.50 per gallon. Gallons used = 300 ÷ 25 = 12 gallons. Fuel cost = 12 × $3.50 = $42.00. Cost per mile = $42.00 ÷ 300 = $0.14 per mile. If gas rose to $4.25, the same trip would cost 12 × $4.25 = $51.00, or $0.17 per mile.
What the Result Means
The total is what the trip's fuel alone will cost — not tolls, wear, or depreciation. Cost per mile is the most useful comparison figure: it lets you weigh driving against flying or shipping, split costs fairly on a shared road trip, or compare two vehicles. Notice how sensitive the total is to MPG: improving from 20 to 30 mpg cuts the fuel bill by a third, which is why fuel economy matters most for high-mileage drivers.
Assumptions and Limitations
This estimates fuel cost only. It assumes a steady average MPG, but real economy swings with speed, terrain, load, weather, air conditioning and traffic, so treat the total as a close estimate rather than an exact figure. Gas prices change constantly and differ from station to station — enter the price you actually expect to pay. For electric vehicles, this tool does not apply; use a cost-per-kWh calculation instead.
Who Uses a Fuel Cost Calculator
Drivers and road-trippers use this to estimate the gas cost of a trip from distance, fuel economy, and price per gallon. Run it to budget a journey, split costs with others, or compare driving against other options. Enter the three values to get the total cost, gallons used, and cost per mile.
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Frequently Asked Questions
How do I calculate the gas cost of a trip?
Divide the trip distance by your vehicle's MPG to get gallons used, then multiply by the price per gallon. For example, 300 miles ÷ 25 mpg = 12 gallons; 12 × $3.50 = $42.00.
Should I use city or highway MPG?
Use the figure that matches your trip. Highway MPG for long interstate drives, city MPG for stop-and-go, or your trip computer's actual average for the best accuracy. A blended real-world number beats the EPA sticker.
How do I find my cost per mile?
Divide the total fuel cost by the trip distance. At $42.00 for 300 miles, that is $0.14 per mile. The calculator shows this automatically.
Does this include a round trip?
Only if you enter the round-trip distance. For an out-and-back journey, double the one-way miles before entering, or run the calculator twice and add the results.
Why does my actual fuel cost differ from the estimate?
Real MPG varies with speed, load, weather, terrain and driving style, and pump prices change between stations and days. The estimate assumes a steady average, so expect small differences on any given trip.
How much does higher MPG really save?
A lot over distance. On a 300-mile trip at $3.50/gal, going from 20 to 30 mpg drops the fuel cost from $52.50 to $35.00 — a third less. The savings grow with the miles you drive.
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