Fuel Cost Calculator
Estimate what a trip will cost in fuel from the distance, your vehicle's fuel economy and the price of fuel. Switch between miles and gallons or kilometres and litres, double it for a round trip, and split the bill between passengers.
Written by Suhaib Hassan. Unit factors follow NIST. Our methodology.
It divides distance by fuel economy to get fuel used, then multiplies by the price you enter.
To budget road trips with your own numbers instead of a flat average. Prices are not pulled live, so enter what you will pay.
Cost by vehicle class
The same trip and fuel price as above, run for typical class averages. These are illustrations, not model ratings. Check fueleconomy.gov for your own vehicle.
| Vehicle class | MPG | Gallons | Trip cost | Cost / mi |
|---|
Popular road trips
Approximate driving distances. Tap one to load it into the calculator.
How the cost is calculated
Miles and gallons
fuel = distance ÷ MPG
cost = fuel × price per gallonKilometres and litres
fuel = distance × (L/100 km) ÷ 100
cost = fuel × price per litreYour numbers
—One US gallon is 3.785412 litres and one mile is 1.609344 km. L/100 km = 235.215 ÷ MPG.
Why real costs differ
Fuel economy varies with driving style, terrain, load, weather and speed. Highway driving usually beats stop-and-go city driving. For the most accurate estimate use the MPG you have actually measured over a few tanks rather than the manufacturer's rating.
For a long trip with mixed roads, price each leg with its own MPG and add them up.
Worked examples
Illustrative trips, each checked by hand.
450-mile road trip
32 MPG, gas at $3.60 a gallon.
14.06 × 3.60 = $50.63
Same trip, thirstier vehicle
22 MPG, same price.
20.45 × 3.60 = $73.64
that is $23.01 more
Metric trip
500 km, 8.0 L/100 km, $1.80 a litre.
40 × 1.80 = $72.00
Ways to reduce fuel costs
- Drive smoothly. Hard acceleration and braking and high highway speeds all cut MPG.
- Keep tires inflated to the recommended pressure and remove roof cargo or excess weight.
- Combine errands into fewer trips and avoid long idling.
- Compare prices along the route and fill up where fuel is cheapest.
By Suhaib Hassan · Reviewed 1 October 2026 · How CalculatePilot verifies formulas →
Sources
- U.S. Department of Energy and EPA, fueleconomy.gov, for vehicle fuel economy ratings.
- NIST Special Publication 811, for gallon, litre, mile and kilometre conversion factors.
Frequently asked questions
Does this account for highway vs city driving?
Use your vehicle's combined MPG for a realistic estimate, or enter the city or highway figure that matches your trip.
How do I find my car's actual MPG?
Divide the miles driven since your last full fill-up by the gallons it took to refill the tank. Tracking this over a few tanks gives a more reliable average than the rated figure. Our Gas Mileage Calculator does this.
Does this account for fuel price changes during a long trip?
No. It uses one price. For a long trip, enter the average price you expect to pay along the route.
Does driving style really affect fuel economy that much?
Yes. Aggressive acceleration and braking, high speeds and idling can reduce fuel economy noticeably compared with smooth, moderate driving, especially in stop-and-go traffic.
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