Car running cost calculator
Everything a car costs you in a year, added up and turned into a monthly figure and a cost per mile. Petrol, diesel or electric.
How this is calculated
Fuel is miles divided by miles per gallon, converted to litres at 4.546 litres to the UK gallon, multiplied by the price per litre. For an electric car it is miles divided by miles per kWh, multiplied by the price per kWh.
Insurance, vehicle tax, servicing, loss in value and other costs are added as annual figures. Finance is entered monthly and multiplied by twelve.
Cost per mile is the annual total divided by the miles you drive, so a car that sits on the drive most of the year has a high cost per mile even if its total is modest.
HMRC's 55p business mileage rate is shown for comparison because it is meant to cover all of a car's running costs, not just fuel.
Rates used · 2026/27
| Litres in a UK gallon | 4.546 |
| Standard vehicle tax | £200 a year from April 2026 |
| HMRC business mileage rate | 55p a mile for the first 10,000 miles |
| Fuel and electricity prices | whatever you pay |
Last checked July 2026. Source: HMRC and gov.uk.
Worked example
At 8,000 miles a year, a 45 mpg petrol car at 139.9p a litre burns £1,131 of fuel. Add £620 of insurance, £200 of vehicle tax and £420 of servicing and it costs £2,371 a year, about £198 a month or 29.6p a mile, before any finance or loss in value.
Common questions
What is included in car running costs?
Fuel or charging, insurance, vehicle tax, servicing, MOT and repairs, any finance, and the loss in value. Parking, tolls and breakdown cover can go in the other line.
Why include loss in value?
Because it is real money. A car worth £15,000 today and £12,000 next year has cost you £3,000, even though no bill arrived.
How does this compare with an electric car?
Switch the fuel to electric and enter miles per kWh and your electricity rate. To set two cars side by side, use the car comparison calculator.
What is a good cost per mile?
It depends on the car and how far you drive. HMRC's 55p business rate is a useful yardstick: well under it is cheap motoring, well over it is expensive.