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Fuel Cost Calculator
See fuel used, total trip cost and cost per mile.
What does a trip really cost in fuel?
Fuel cost sounds simple to calculate, but most drivers just estimate. The exact formula: divide the distance by your fuel economy (mpg) to get gallons used, then multiply by the price per gallon to get total trip cost. Cost per mile comes from dividing total cost by distance — a figure that's genuinely useful for comparing different cars or alternate routes.
If you know your car's efficiency as gallons per 100 miles instead of mpg, the unit-switch button above converts it in the background using "100 divided by gallons-per-100-miles equals mpg." Enter your average monthly mileage and the same rate is used to estimate your monthly fuel cost too — handy for household budgeting or comparing commute options.
Frequently asked questions
Why does this calculator show monthly fuel cost separately?
Because trip distance and monthly mileage are two different numbers. If you enter your average monthly mileage, the calculator shows an estimate of your monthly fuel cost using the same fuel economy figure, alongside the cost of this specific trip.
What's the difference between mpg and gallons per 100 miles?
They describe the same thing in opposite directions: mpg is how many miles you travel per gallon (higher is better), while gallons per 100 miles is how much fuel it takes to cover 100 miles (lower is better). The conversion is: mpg equals 100 divided by gallons per 100 miles.
My car's real-world mpg is different from the window sticker, what should I do?
EPA window-sticker figures come from standardized testing and real city driving is often less efficient. It's best to calculate your own actual mpg by filling the tank, noting the miles driven, and dividing miles by gallons used — then enter that number here.
Does the price at different stations matter?
Yes, and this tool doesn't distinguish between them — it just uses whatever number you enter in the price-per-gallon field. If you fill up at a mix of prices, enter a weighted average for a more accurate result.