Fuel Cost Calculator
Work out the petrol or diesel cost of any journey
Work out what the fuel for a journey will cost: put in the distance, your car's miles per gallon and the price of petrol or diesel, and you'll get the total for a one-way trip or a return, with the option to split it between passengers. It's the quick sum for a commute, a road trip, or working out what to charge someone for a lift.
Journey Details
Getting a fuel estimate that matches reality
The figure a fuel calculator gives is only as honest as the MPG you feed it, and the number on the brochure is rarely the number you get. Official economy figures come from controlled laboratory tests, so real-world driving — with hills, traffic, cold starts and a boot full of luggage — typically returns 10 to 20% worse. The most reliable MPG is your own: fill the tank, note the mileage, drive normally, and at the next full fill divide the miles covered by the gallons it took.
Driving style makes a real difference too; steady speeds and gentle acceleration save a noticeable amount, while motorway speeds above about 60mph push consumption up sharply, because air resistance climbs with the square of speed. One unit trap to watch: a UK gallon is 4.55 litres, not the US gallon's 3.79, so an MPG figure from an American source will flatter a British car.
❓ Frequently Asked Questions
How do I calculate the fuel cost of a journey? ▼
Fuel cost = (distance ÷ fuel economy) × fuel price. Enter your journey distance, your car's MPG or L/100km, and the price of fuel, and the calculator does the maths instantly — including return trips and splitting the cost between passengers.
Where do I find my car's MPG? ▼
Your car's official MPG is in its handbook or on the manufacturer's website. Many cars also display average MPG on the dashboard trip computer. Real-world economy is usually a bit lower than the official figure, so use your dashboard reading for the most accurate cost.
What's the difference between UK and US MPG? ▼
A UK gallon (4.546 litres) is larger than a US gallon (3.785 litres), so the same car shows a higher MPG figure in the UK than the US. Make sure you pick the right unit — our calculator supports UK MPG, US MPG, L/100km and km/L.
Can I split the fuel cost with passengers? ▼
Yes — enter the number of people sharing the journey in the "Split between" box and the calculator shows the cost per person. Great for car-sharing, lift money and splitting road trip costs fairly.
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