This fuel cost calculator estimates how much a trip will cost in gas, petrol or diesel. It works with US MPG, UK MPG and metric L/100 km, so it suits drivers in the US, UK, Canada and Australia.
How fuel cost is calculated
- US: gallons = miles ÷ MPG; cost = gallons × price per gallon
- UK: litres = (miles ÷ MPG) × 4.546; cost = litres × price per litre
- Metric: litres = km × L/100 km ÷ 100; cost = litres × price per litre
Worked example
A 300-mile trip in a car that gets 30 MPG uses 10 US gallons. At $3.50 a gallon, the trip costs $35, or $70 for the round trip.
Frequently asked questions
Why does UK MPG differ from US MPG?
A UK (imperial) gallon is 4.546 litres while a US gallon is 3.785 litres, so the same car shows a higher MPG figure in the UK.
How can I make the estimate more accurate?
Use your car’s real-world efficiency from its trip computer rather than the official figure, which is often higher than what you get on the road. If you drive electric, use the EV charging cost calculator.