Fuel cost calculator
What a journey costs in petrol or diesel, with wear and tear, split between passengers.
Fuel cost
£13.83
- Distance
- 100 miles
- Fuel used
- 10.1 litres
- Fuel per mile
- 13.8p
- Economy
- 45 mpg
Show workings
- Distance100 miles = 100 miles (160.93 km)
- Fuel used100 miles ÷ 45 mpg × 4.54609 litres per UK gallon = 10.1 litres
- Fuel cost10.1 litres × 136.9p per litre = £13.83
- Cost per mile£13.83 ÷ 100 miles = 13.8p
How the fuel cost is worked out
The calculator turns your fuel economy into the litres of fuel the journey uses, then multiplies by the price per litre. A UK gallon is 4.546 litres, so for a car measured in MPG:
litres = miles ÷ MPG × 4.546 · cost = litres × price per litre
Worked example
A 100 mile trip in a car that does 45 MPG uses 100 ÷ 45 × 4.546 = 10.1 litres. At 145.9p a litre that is 10.1 × £1.459 = £14.74, or about 14.7p a mile. Shared between two people, it's £7.37 each.
Questions
Where do I find my car's MPG?
Most cars show an average MPG on the dashboard or trip computer. Your handbook or the manufacturer's website also lists an official figure, though real-world driving is usually a little worse.
Why is US MPG different?
A US gallon is smaller (3.785 litres) than a UK gallon (4.546 litres), so the same car shows a lower MPG in the US. Pick the unit your figure came from.
Can I enter the price in pounds?
Yes. Type 1.45 and it is read as £1.45 a litre (145p). Anything under 10 is treated as pounds.
What does wear and tear cover?
Tyres, servicing, brakes and repairs, spread over the miles you drive. Around 5–15p a mile is typical for a family car; add depreciation if you want the full cost of a trip. HMRC's 45p a mile mileage allowance covers fuel, wear and tear and depreciation together.
Can I enter the price per gallon?
Yes. Choose per UK or US gallon and type the price as shown at the pump, e.g. $3.29. It's converted to a price per litre for the sum.
How accurate is it?
It's as accurate as the figures you enter. Traffic, speed, air conditioning and load all change real fuel use, so treat the result as a good estimate rather than an exact amount.