BuildSums

EV charging cost calculator

Enter your battery size, charge level and tariff to see what a home charge costs, how long it takes and the cost per mile.

Your measurements

You’ll need your car’s usable battery size in kWh, and your electricity unit rate. If you’re on an EV tariff, use its off-peak rate. The boxes start with example figures, and the result updates as you type.

In your car’s handbook or spec sheet
7.4 wallbox, 2.3 3-pin plug
10 on a wallbox, more on a plug
Price cap: 26.32p
Optional, from your trip computer

Result

Fill in the measurements to see what to order.

Figures checked 25 October 2026. See the sources, or report a problem.

How this is worked out

Energy into the battery = battery size × (target % − starting %). Some energy is lost as heat in the charger and the car, so energy from the supply = energy into the battery ÷ (1 − losses). Cost = energy from the supply × unit rate.

Time = energy from the supply ÷ charger power. Real charging slows down as the battery gets full, so a charge to 100% takes longer than the simple sum suggests.

We default to 10% losses, the low end of the 10 to 25% range E.ON Next gives, which fits a good wallbox in mild weather. The default unit rate is Ofgem’s price cap for 1 October to 31 December 2026. Most EV tariffs charge much less overnight, so put in your own rate.

Worked example

A car with a 60 kWh battery charged from 20% to 80% adds 36 kWh. With 10% losses that’s 40 kWh from the supply. At 26.32p per kWh it costs £10.53, and on a 7.4kW wallbox takes about 5 hours 24 minutes. At 3.5 miles per kWh that’s 126 miles, about 8.4p a mile.

Ways to cut the cost

  • Use an EV tariff with a cheap overnight window, and set the car or charger to charge only then.
  • Day to day, charging to 80% is usually enough and is kinder to most batteries.
  • If you have solar panels, a charger that follows surplus solar can fill the car for very little in summer.

Questions people ask

How much does it cost to charge an electric car at home?

It depends on your battery and your tariff. Adding 40 kWh at the price cap rate of 26.32p per kWh, with 10% charging losses, costs about £11.70. On an off-peak EV tariff it can be a fraction of that.

How long does a 7kW charger take?

A 7kW wallbox (7.4kW on most single-phase homes) adds about 7 kWh an hour, before losses. A 40 kWh top-up takes roughly 6 hours.

Is charging from a 3-pin plug more expensive?

Per kWh you pay the same rate, but more is lost as heat. E.ON Next says losses can reach 25% on a 3-pin plug on a cold night, against about 10% on a good wallbox on a warm day. A 3-pin plug is also slow, at about 2.3kW.

What’s a good miles per kWh figure?

Many family EVs manage 3 to 4 miles per kWh in mild weather, less in winter and at motorway speeds. Your car’s trip computer shows your own figure.

Sources

Trade review pending. A named tradesperson will check this calculator, and their name and qualifications will appear here.

Figures last checked 25 October 2026. Read how we calculate and our disclaimer. Found a mistake? Tell us.