To calculate the cost of a car journey, you need three key pieces of information: the total distance of your trip, your vehicle’s fuel efficiency (in miles per gallon or litres per 100km), and the current fuel price per litre. The basic formula is: Fuel Cost = (Distance ÷ Fuel Efficiency) × Fuel Price. You can then add any additional costs like tolls, parking, or congestion charges to get your total journey cost.

The average cost per mile to drive in the UK in 2026 ranges from 12p to 18p per mile for fuel alone, depending on your vehicle’s efficiency and current fuel prices. When you include maintenance, insurance, and depreciation, the total cost per mile rises to around 40p to 60p per mile. Electric vehicles typically cost 4p to 8p per mile for electricity, making them significantly cheaper to run than petrol or diesel cars.

A journey cost calculator provides a good estimate based on the inputs you provide. However, actual costs can vary due to driving conditions (city vs motorway), driving style, vehicle load, weather, and route taken. Fuel efficiency figures are typically based on official WLTP tests, but real-world efficiency can be 10-20% lower. For the most accurate results, use your vehicle’s actual fuel consumption data and current fuel prices from your local station.

To split fuel costs between passengers, simply divide the total fuel cost by the number of people sharing the cost. For example, if your total fuel cost is £50 and there are 4 passengers (including the driver), each person would pay £12.50. Some people prefer to split costs equally, while others may calculate based on who benefits most from the journey. Our calculator automatically shows the cost per person when you enter the number of passengers.

You can find your car’s official fuel efficiency in the vehicle handbook or on the manufacturer’s website (measured in miles per gallon or litres per 100km). However, real-world efficiency is typically 10-20% lower than official figures. For a more accurate estimate, calculate your actual fuel consumption by filling up your tank, recording the miles driven, and dividing the litres used by the distance. Small cars typically achieve 45-55 mpg, medium cars 35-45 mpg, and large SUVs 25-35 mpg.

Electric cars are generally cheaper for long journeys when charging at home or using workplace chargers, with costs around 4p to 8p per mile compared to 12p to 18p per mile for petrol or diesel. However, using rapid public chargers can increase costs to 15p to 25p per mile, making them comparable to or more expensive than efficient petrol cars. Electric cars also benefit from lower maintenance costs and exemption from congestion charges in some cities.

Toll roads can significantly add to your journey costs. In the UK, major toll roads include the M6 Toll (£7.40 for cars), Dartford Crossing (£2.50 per crossing), and various bridges and tunnels. Some routes have congestion charges like London’s ULEZ (£12.50 daily) and Congestion Charge (£15 daily). When planning a journey, check if alternative routes avoid tolls and calculate whether the time saved justifies the extra cost. Our calculator includes fields for tolls and other charges.

The cheapest way to calculate fuel costs for a road trip is to use our free online journey cost calculator. Simply enter your total distance, vehicle fuel efficiency, and current fuel price. The calculator instantly shows your total fuel cost, cost per mile, and can split costs between passengers. For the most accurate results, use your vehicle’s actual fuel consumption rather than official figures, and check current fuel prices at stations along your route.