Two questions, two answers
This calculator answers two related questions. What will this charge cost? depends on the battery energy you add and the losses on the way in. What does driving cost? depends on how efficient the car is and where you charge. The first is handy at the charger; the second is what you need to compare an EV with a petrol or gasoline car.
Cost of a charging session
Charging isn't perfectly efficient: some energy is lost as heat in the charger, cable and battery. The U.S. Department of Energy puts the wall-to-battery loss at about 16%, so we default to 84% efficiency. Losses vary with the car, the charger, the battery's temperature and how full it is; a 2021 peer-reviewed study of AC charging measured roughly 80–87% depending on the charging current and number of phases used. If your car or charger reports the energy delivered from the wall, use that instead.
Worked example: a 60 kWh battery charged from 20% to 80% takes in 36 kWh. At 84% efficiency that is 42.9 kWh from the wall; at 18¢/kWh the session costs about $7.71.
Cost per mile or per kilometre
Official EV efficiency figures in the US (EPA) and on WLTP labels in the UK and Australia are measured from the wall socket, so they already include charging losses. Don't add losses again. Your car's dashboard, on the other hand, usually reports energy taken from the battery; if you use that figure, add the charging loss in the “extra losses” field.
Real-world consumption is typically worse than the label in cold weather, at motorway speeds and on short trips with heating on. The monthly cost chart shows how quickly public charging changes the picture: rapid-charger prices are often several times a home tariff, so even a modest share of public charging can double the cost per mile.
Reference home electricity prices
| Default | Country | Value | Source and period |
|---|---|---|---|
| Home electricity | US | 18.31¢/kWh | U.S. EIA, Electric Power Monthly, Table 5.6.A, July 2026 (preliminary) |
| Home electricity | UK | 26.32p/kWh | Ofgem, 1 Oct – 31 Dec 2026 |
| Home electricity | Canada | — | No verified national figure on file — the field asks for your own rate. |
| Home electricity | Australia | — | No verified national figure on file — the field asks for your own rate. |
We don't pre-fill public charging prices: they vary by network, charger speed, membership and time of day, and there is no official national average we could cite. Use the price shown in your charging app. If you're on an EV or time-of-use tariff, enter your off-peak rate as the home price — that is usually where the biggest savings are.
Weighing up whether to switch? The Gas vs Electric Car calculator adds purchase price, maintenance and a break-even year.
Sources
- U.S. EPA — Fuel economy and EV range testing (MPGe and kWh/100 mi include charging losses)
- U.S. DOE — Fact of the Week #1045: about 16% energy loss from wall to battery
- FuelEconomy.gov — Where the energy goes: electric cars
- Vehicles (MDPI), 2021 — Influence of Charging Losses on Energy Consumption and CO2 Emissions of Battery-Electric Vehicles
- Ofgem — Energy price cap unit rates
Results are estimates based on the figures you enter and the stated assumptions. They are not financial, tax, legal or engineering advice. Spotted a problem? Tell us.