Fuel Cost Calculator
Estimate the fuel cost of any trip from the distance, your vehicle's efficiency, and the price of fuel.
Last reviewed July 1, 2026
Planning a road trip or working out your commuting costs? This calculator estimates how much fuel a journey will use and what it will cost, based on the distance, your vehicle's efficiency, and the current price of fuel. It works in both US units (miles, MPG, price per gallon) and metric (km, litres per 100 km, price per litre).
Enter your numbers to see the total fuel cost, the amount of fuel used, and the cost per mile or kilometre — handy for budgeting or splitting costs with passengers.
The Fuel Cost formula
US: Fuel used = Distance ÷ MPG, Cost = Fuel used × price per gallon; Metric: Fuel used = Distance ÷ 100 × (L/100km), Cost = Fuel used × price per litreDistance = trip length · MPG or L/100km = your vehicle's fuel efficiency · price = the cost of fuel per gallon or litre.
Worked example
A 300-mile trip in a car doing 30 MPG uses 300 ÷ 30 = 10 gallons. At $3.50 a gallon that's 10 × 3.50 = $35 in fuel, or about 11.7 cents per mile.
How trip fuel cost is worked out
In US units, fuel used = distance ÷ MPG, and cost = fuel used × price per gallon. In metric, fuel used = distance ÷ 100 × (litres per 100 km), then multiplied by the price per litre.
Real-world consumption is usually a little worse than the official figure, especially in city driving, cold weather, or with a loaded vehicle — so treat the result as a good estimate and round up a touch for budgeting.
Frequently asked questions
▶How do I calculate the fuel cost of a trip?
Divide the distance by your fuel efficiency to find how much fuel you'll use, then multiply by the price of fuel. This calculator does it in both US and metric units.
▶Does this include wear, tolls or parking?
No — it's fuel only. For the full cost of driving, add tolls, parking, and a rough allowance for wear and maintenance on top.
▶How do I calculate the cost of a road trip?
Divide the distance by your vehicle's fuel efficiency to find the fuel used, then multiply by the price of fuel. This calculator does it in both US (MPG) and metric (L/100km) units.
▶How do I split fuel costs between passengers?
Work out the total trip fuel cost, then divide by the number of people sharing. For a rough per-person figure, take the total and split it evenly.
▶How do I convert MPG to litres per 100 km?
Divide 282.5 by the MPG figure (using US gallons). So 30 MPG is about 282.5 ÷ 30 ≈ 9.4 L/100km. The calculator lets you work in whichever unit you prefer.
▶Why does my real fuel use exceed the estimate?
Official efficiency figures are measured in ideal conditions. City driving, cold weather, air conditioning, a heavy load or a roof rack all raise consumption, so round up a little for budgeting.
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Open calculator →Disclaimer: Fuel Cost Calculator results are estimates for general information and education only, and are not financial, tax, legal or medical advice. Verify important decisions with a qualified professional.