What a mile costs
A car doing 3.5 miles per kWh costs about 2.2p a mile charged at home on an off-peak EV tariff, against 17.5p for a 45 mpg petrol car at 173.46p a litre. Public rapid charging, at 77p per kWh, costs 22p a mile, more than petrol for that car.
| Car and where it fills up | Price | Per mile | For 8,000 miles |
|---|---|---|---|
| Electric, home off-peak EV tariff | 7.6p per kWh | 2.2p | £174 |
| Electric, home at the price cap | 26.3p per kWh | 7.5p | £602 |
| Electric, public slow or fast charger | 54p per kWh | 15.4p | £1,234 |
| Electric, public rapid charger | 77p per kWh | 22p | £1,760 |
| Petrol, 45 mpg | 173.46p a litre | 17.5p | £1,402 |
| Diesel, 50 mpg | 197.58p a litre | 18p | £1,437 |
The data behind this table
Electricity at the Ofgem cap for October to December 2026 and Intelligent Octopus Go's off-peak rate checked 3 October 2026; public prices are the Zapmap averages for August 2026; petrol and diesel are the DESNZ averages for the week of 28 September 2026. The efficiency and mpg figures are examples.
Road tax and the pay-per-mile charge
Electric cars have paid vehicle tax since 1 April 2025: £10 in the first year, then £200 a year, the same as petrol and diesel. An electric car with a list price over £50,000 adds £440 a year for 5 years; for petrol and diesel the threshold is £40,000. From 1 April 2028 electric cars also pay eVED at 3p a mile, £240 a year at 8,000 miles, and plug-in hybrids 1.5p. Our pay-per-mile tax guide compares it with fuel duty.
The Electric Car Grant
New electric cars listed at £37,000 or less can come with £3,750 or £1,500 off, depending on how sustainably the car is made. The dealer takes it off the price, so you do not apply. The grant has been available since 16 July 2025, and in December 2025 the government extended it to 2030. Only models on the government list qualify.
For a home charger, renters, flat owners and households with on-street parking can get 75% of the cost up to £500 until 31 March 2027: see our EV chargepoint grant guide. To see how many public chargers your area has, use our EV chargers by council map.
How the calculator works
Charging is your miles divided by the car's miles per kWh, priced at your home rate for the share charged at home and at the public price for the rest. Fuel is your miles divided by the mpg, times 4.546 litres to a UK gallon, at the average pump price. Tax is the standard rate for both cars from their second year, with eVED counted only for the months from April 2028 within the years you keep the car, starting this month.
We leave out the purchase price, depreciation, insurance and servicing: there is no reliable public data comparing them for electric and petrol cars of the same kind. We also leave out the electricity lost in charging and the standing charge you pay anyway.
Frequently asked questions
Is an electric car cheaper to run than petrol?
Usually, if you can charge at home. At 8,000 miles a year, a car doing 3.5 miles per kWh charged 80% at home on an off-peak tariff and 20% on rapid chargers costs about £491 a year, against £1,402 for a 45 mpg petrol car. Charged only on rapid public chargers it costs £1,760.
How much does it cost to charge an electric car at home?
About 2.2p a mile on an off-peak EV tariff at 7.6p per kWh, or 7.5p a mile at the price cap rate of 26.3p, for a car doing 3.5 miles per kWh.
What road tax does an electric car pay?
£200 a year from the second year, the same as petrol and diesel cars, plus £440 a year for 5 years if the list price was over £50,000. From 1 April 2028 electric cars also pay 3p a mile in eVED. See our pay-per-mile tax guide.
Does the calculator include the Electric Car Grant?
It notes it but does not take it off, because the calculator compares running costs, not purchase prices. The grant gives £3,750 or £1,500 off new electric cars listed at £37,000 or less, taken off by the dealer.
Why are depreciation and insurance left out?
There is no reliable public data to compare them for electric and petrol cars of the same kind, so we leave them out rather than guess.
Data sources
- Ofgem, energy price cap for 1 October to 31 December 2026: electricity 26.32p per kWh by direct debit.
- Octopus Energy, Intelligent Octopus Go: off-peak rate 7.6p per kWh from 11:30pm to 5:30am, checked 3 October 2026.
- Zapmap, charging price index, August 2026 (updated 4 September 2026): 77p per kWh on rapid and ultra-rapid chargers, 54p on slow and fast ones, pay as you go.
- Department for Energy Security and Net Zero, weekly road fuel prices, week of 28 September 2026: petrol 173.46p and diesel 197.58p a litre, duty 52.95p a litre.
- GOV.UK, vehicle tax rates (updated 9 September 2026): £200 a year from the second payment, £10 first payment for a zero emission car, £440 expensive car supplement.
- HM Treasury and HMRC, Electric Vehicle Excise Duty (eVED) policy paper, 13 July 2026: 3p a mile for electric cars and 1.5p for plug-in hybrids from 1 April 2028.
- Department for Transport, Electric Car Grant launched (15 July 2025), eligible cars and the extension to 2030 (3 December 2025).
- Office for Zero Emission Vehicles, changes to chargepoint grants from 1 April 2026 (updated 7 July 2026) and electric vehicle chargepoint grants.