Journey cost calculator
What a trip actually costs in fuel or charging. Set it to your commute and the annual figure is usually larger than expected.
How this is calculated
Distance is doubled if you tick return. Fuel used is that distance divided by miles per gallon, converted to litres at 4.546 litres per gallon, then multiplied by the pump price.
For an electric car the distance is divided by miles per kWh and multiplied by the electricity rate instead.
Tolls and parking are added per journey, then everything is multiplied by journeys a week and weeks a year.
This is fuel and direct costs only. It does not include the servicing, tyres and depreciation the mileage causes, which is why HMRC values business mileage at 45p a mile rather than the fuel cost alone.
Rates used · 2026/27
| Imperial gallon | 4.546 litres |
| HMRC mileage rate | 45p a mile to 10,000 business miles, then 25p |
| Typical petrol economy | 40 to 55 mpg |
| Typical EV efficiency | 3.0 to 4.5 miles per kWh |
Last checked July 2026. Source: HMRC and gov.uk.
Worked example
An 18 mile commute each way is 36 miles a day. At 45 mpg and 139.9p a litre that is £5.09 a journey. Five days a week for 46 weeks is 230 journeys, 8,280 miles and £1,170 a year in fuel alone, or £98 a month.
Common questions
Why is the HMRC rate so much higher than the fuel cost?
Because 45p a mile is meant to cover servicing, tyres, insurance and depreciation as well as fuel. If your employer pays less than that for business mileage you can claim the difference as tax relief.
Should I use the official mpg figure?
Use what you actually get. Motorway driving at a steady speed often beats the official figure, while short cold trips can be 30% worse.
Does this work for a commute?
That is what it is best at. Set weeks to around 46 to allow for holidays, and the annual figure is usually the one that changes people's minds about a job or a house.
What about an electric car on public chargers?
Enter the public rate rather than the home rate. Rapid charging is commonly three times the home cost, which changes the answer completely.