What does home charging cost compared with public charging?

An electric car has no single fuel price

A petrol car has one price per litre on a sign by the road. An electric car has at least two: the rate on your electricity bill and whatever the charging network asks at the point you happen to stop at. The useful question is therefore not what electricity costs, but what your particular mix of home and public charging costs over a year.

The EV charging cost calculator asks for both prices, the share you charge at home, and your own distance and consumption, then reports the cost per year and per 100 km or 100 miles.

Charging loss is not a rounding error

The meter bills you for more energy than the battery receives. Cable and charger losses, plus the energy spent conditioning the battery, typically account for somewhere around 5-10% on home AC charging. Because the loss sits between the socket and the battery, it is applied by dividing: 2,700 kWh into the battery at an 8% loss means paying for about 2,935 kWh. Ignore it and you understate your real cost by roughly the same percentage.

Work the same year two ways

Take 15,000 km a year at 18 kWh per 100 km — 2,700 kWh into the battery, 2,935 kWh bought. Charge it all at home at 0.30 per kWh and the year costs about 880, or 5.87 per 100 km. Charge it all in public at 0.60 and the same year costs about 1,761, or 11.74 per 100 km. A realistic 80/20 split lands at 1,057 a year and 7.04 per 100 km.

• The home share is a share of energy, not of charging sessions — public sessions are usually larger.
• Winter consumption can be a quarter higher than a summer figure, so run both.
• If you use several networks, take a weighted average of the prices you actually pay.

Compare it with the car you had before

Cost per 100 km or per 100 miles is the figure that transfers between cars, because it does not depend on how much you drive. Work out the same number for a petrol or diesel car with the Fuel cost calculator and put them side by side. Charging mostly at home usually wins comfortably; charging almost entirely in public narrows the gap and, at a high enough public price, can close it.

What the energy price leaves out

A charging subscription with a monthly fee, the cost of installing a home charge point, parking at the chargepoint, and idle fees all change the real total without changing the price per kWh. Keep them separate rather than folding them into the rate, so you can see which decision each one belongs to. If your home rate has cheap night hours, the honest input is the average price you actually pay across the charging you do.

It is also worth pricing the rest of the meter at the same time. The Electricity cost calculator does the same arithmetic for anything else that runs on the same tariff, which is often where a surprisingly large share of the bill turns out to be.