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Fuel Cost Calculator
Enter your trip distance, your vehicle’s fuel efficiency and the fuel price, and get the fuel needed and the total cost instantly — including a round-trip option and a per-passenger split.
Costs are estimates: real consumption varies with speed, traffic, load, weather and driving style, and pump prices vary by station.
How it works
First the fuel needed is found from distance and efficiency. With mpg it is fuel (gallons) = distance (miles) ÷ mpg; with litres per 100 km it is fuel (litres) = distance (km) ÷ 100 × litres per 100 km; with km per litre it is fuel (litres) = distance (km) ÷ km per litre. Gallons and litres convert at 1 gallon = 3.78541 litres, and miles and kilometres at 1 mile = 1.60934 km. Then cost = fuel × price, cost per mile (or km) = cost ÷ distance, and cost per passenger = cost ÷ passengers. Worked example: 300 miles at 30 mpg needs 300 ÷ 30 = 10 gallons; at $3.50 per gallon that is 10 × $3.50 = $35.00, or $35.00 ÷ 300 = $0.117 per mile. The same trip in metric — 482.8 km at 7.84 L/100 km — needs 482.8 ÷ 100 × 7.84 = 37.85 litres (10 gallons), the same answer by a different route.
Frequently asked questions
What does mpg mean, and how does it relate to litres per 100 km?
Mpg is miles travelled per gallon of fuel — higher is more efficient. Litres per 100 km is fuel used per 100 km — lower is more efficient. 30 mpg (US) is about 7.84 L/100 km. This calculator accepts either, so you never have to convert by hand.
Why is my real fuel bill higher than this?
The calculator uses one steady efficiency figure. Real driving mixes city and highway, and cold starts, air conditioning, roof boxes and heavy loads all raise consumption. Treat the result as a planning estimate, then add a small margin for a long trip.
Should I use the price at one station or an average?
Use the price you expect to pay along the route. Prices vary by station and region, so a trip that crosses state lines will not match a single-station price exactly.
Does a round trip just double the one-way cost?
Yes, if the return route and conditions match. Tick the round-trip box and the distance — and therefore fuel and cost — doubles.
How do I split the cost fairly between passengers?
Enter the number of people sharing the car and the tool divides the total evenly. Fuel is usually the only cost split this way; tolls and parking are separate.
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