EV charging cost calculator

How to read it

The four bars show what the same yearly mileage costs in four ways:

• Home on your chosen EV tariff. The off-peak rate from the drop-down: Intelligent Octopus Go, EDF GoElectric, E.ON Next Drive Smart, Octopus Go or British Gas EV Power.
• Home at the standard rate. The Ofgem price cap, 26.32p/kWh (GB average, Direct Debit, 1 October to 31 December 2026).
• Public rapid chargers. 79p/kWh, Zapmap’s September 2026 average for chargers of 50kW and above.
• A petrol car. Set the mpg with the slider. Unleaded is priced at 174.88p a litre, the DESNZ average on 5 October 2026.

The line under the bars shows how much charging at home on your tariff saves compared with petrol and with public rapid charging.

The calculator opens on 7,100 miles, the DfT average for all cars in England. The average battery-electric car covers more: 9,400 miles (DfT NTS0901, 2025). Move the mileage slider to your own figure.

What it assumes

• Efficiency. 0.301 kWh a mile is the EV Database average across listed models, which is 3.32 miles per kWh. The slider rounds to 3.3, so results run about 1% above the 0.301-based figures in our guides. At the defaults, the Intelligent Octopus Go bar is 7,100 ÷ 3.3 = 2,152 kWh × 7.6p, about £164.
• VAT. Home rates are for Great Britain with domestic electricity at 0% VAT until 31 March 2027. If VAT returns to 5% on the same pre-VAT prices, home figures rise 5% (our derivation). Public charging is always 20% VAT, according to HMRC. In Northern Ireland, VAT stays at 5% and the GB price-cap figure is not the rate that applies.
• Charging losses. Not counted. ADAC measured 5.1% to 7% lost on an 11kW wallbox and 12.7% to 24.2% on a 2.3kW socket, so real home costs are a little higher.
• Public rates. An average. Tesla Superchargers, memberships and promotions can differ.
• Petrol. Whatever mpg you choose, at the 5 October price.

What it leaves out

The calculator prices electricity for the car. It does not include your standing charge, which you pay with or without a car, or the day rate on the rest of your house. EV tariffs charge more by day than the cap: Intelligent Octopus Go’s day rate averages 36.70p. A low-mileage, daytime-heavy home can lose more than the car saves. Our EV tariff comparison works through whole-home annual costs and gives a break-even of about 4,570 miles a year for Intelligent Octopus Go with none of the house’s 2,500 kWh moved to the night.

It also excludes the charger and its installation. The installation cost guide covers that.

Where to go next

• How much does it cost to charge an electric car at home? gives the cost per mile, per full charge and per year for 40, 60, 77 and 100 kWh batteries.
• Best EV tariffs compares the rates, windows and requirements of the main suppliers.
• Intelligent Octopus Go explained covers the cheapest smart tariff for most drivers.
• How long to charge turns battery size and charger power into hours.