Planning a road trip or a daily commute? This fuel cost calculator, also called a gas calculator or trip cost calculator, shows how much fuel you need and what the drive will cost. Enter the distance, your car’s fuel economy and the price of gas or petrol, then split the cost between everyone in the car.
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Choosing the right units
- Metric: distance in kilometres, economy in litres per 100 km, price per litre. Used in most of Europe, Asia, Australia and Canada.
- US: distance in miles, economy in miles per US gallon, price per gallon.
- UK: distance in miles, economy in miles per imperial gallon, but fuel is sold per litre. The calculator converts this for you.
How fuel cost is calculated
With L/100 km: fuel needed = distance × economy ÷ 100, and cost = fuel needed × price per litre. With MPG: fuel needed = distance ÷ MPG. A UK imperial gallon is 4.546 litres, which is why UK MPG figures look higher than US ones for the same car.
Tips to save fuel on a trip
- Keep tyres at the recommended pressure.
- Drive at a steady speed; high motorway speeds use noticeably more fuel.
- Remove roof racks and extra weight you do not need.
Frequently asked questions
Where do I find my car’s fuel economy?
Your trip computer usually shows it. Official figures are often optimistic, so real-world economy is typically 10–20% worse, especially in city driving.
How much will gas cost for my trip?
Divide the trip distance by your car’s MPG to get the gallons needed, then multiply by the price per gallon. For example, a 300-mile trip in a car that does 30 MPG needs 10 gallons; at 3.50 a gallon that is 35. With L/100 km, multiply the distance by the economy figure and divide by 100 to get litres.
Results are estimates. Related: EV vs gas cost calculator · Total cost of ownership