EV charging
EV home charging cost UK: a worked 7 kW example
A real worked example of what a 20–80% EV top-up costs on an off-peak tariff, a standard tariff and a public rapid charger in the UK.
The example car and top-up
Take an illustrative 60 kWh battery charged from 20% to 80%. The energy added to the battery is 60 × 60 ÷ 100 = 36 kWh. Charging is not perfectly efficient, so at 90% efficiency on a home wallbox the meter records about 36 ÷ 0.9 = 40 kWh.
That 40 kWh figure, not the 36 kWh in the battery, is what you pay for. Forgetting the losses is the most common reason a home-charging estimate comes out low.
Same top-up, three prices
At an illustrative off-peak EV tariff of 7p per kWh, 40 kWh costs 40 × £0.07 = £2.80. At an illustrative standard rate of 24.5p per kWh it costs 40 × £0.245 = £9.80 — three and a half times as much for exactly the same energy.
On a public rapid charger at an illustrative 79p per kWh, with about 95% efficiency, you would pay for roughly 36 ÷ 0.95 ≈ 37.9 kWh, or about £29.94. Rapid charging buys you time, not value.
Turn it into pence per mile
If the car averages 3.5 miles per kWh, the 36 kWh top-up gives about 126 miles. Off-peak that works out at £2.80 ÷ 126 ≈ 2.2p per mile; at the rapid charger it is about 23.8p per mile. Prices here are examples — use the rates on your own bill and the charge point’s tariff.
