Home charging, public AC or rapid — enter your rate in pence per kWh and see what the journey actually costs, next to the petrol equivalent.
Electric cars are rated in miles per kWh rather than MPG. The maths is simpler than petrol:
A typical UK EV does 3.2–4.0 miles per kWh in mixed driving. At 3.5 mi/kWh and 24.5p per kWh, 100 miles costs about £7.00 — roughly 7p a mile. The same trip in a 45 MPG petrol car at 145.9p a litre costs about £14.75, so the EV is around half price on home charging and far cheaper than a rapid charger comparison suggests.
| Where you charge | Typical rate | Cost per 100 miles* |
|---|---|---|
| Home, standard variable tariff | 22–26p/kWh | £6.30–£7.40 |
| Home, off-peak EV tariff (overnight) | 7–10p/kWh | £2.00–£2.90 |
| Public AC (slower, street/park) | 40–55p/kWh | £11.40–£15.70 |
| Public rapid (50–150 kW, motorway) | 65–85p/kWh | £18.60–£24.30 |
*At 3.5 miles per kWh. Real cost depends on temperature, speed and how much you use the heater.
Petrol cars are at their most efficient at a steady 50–60 mph; EVs are the opposite. Above about 60 mph, aerodynamic drag dominates and consumption can rise 25–35%. Cold weather adds another hit: a lithium pack loses usable capacity below about 5°C and cabin heating draws 1.5–3 kW. Expect 20–30% worse efficiency in a UK winter, and pre-condition the car while it is still plugged in.
The kWh you pay for is not all kWh that reach the battery. AC charging loses 5–12% in the onboard charger; DC rapid charging loses 2–5%. If you want the true cost, add around 10% to the kWh figure for home charging. It rarely changes the conclusion — home charging still beats petrol by a wide margin.
On home charging, yes: roughly 5–10p a mile against 15–20p for petrol and diesel. On public rapid charging only, the gap narrows to almost nothing. If you cannot charge at home or work, the cost case for an EV is much weaker — that, not the sticker price, is the number worth checking before you buy.
The main calculator handles petrol, diesel and EV side by side, with cost per mile and CO₂.
At 24.5p per kWh and 3.5 miles per kWh, a full 60 kWh charge costs about £14.70 and covers roughly 210 miles — around 7p a mile.
Most UK EVs average 3.2–4.0 miles per kWh in mixed driving, dropping to 2.5–3.0 in winter or at sustained motorway speeds.
Sometimes. At 75p per kWh and 3.5 mi/kWh you pay about 21p a mile, which is close to a 45 MPG petrol car. Home charging is where the saving lives.