EV Charging Cost Calculator
Work out what one charge costs: battery size, charge level now and target, your price per kWh and charging losses give the energy drawn from the grid and the bill. It doesn't estimate charging time or per-minute station fees.
Units
Before you plug in
- Charging losses depend on how you charge. ADAC measured about 5–7% at an 11 kW wallbox, 13–24% from a regular household socket and 5–15% for DC fast charging, so the default 90% efficiency fits a home wallbox. Lower it for a household socket.
- Use the usable (net) battery capacity, not the gross figure, and charge levels from the car's display. If a station bills per minute, per session or adds idle fees instead of per kWh, this calculator doesn't cover it.
- For cost per 100 miles, enter the rated kWh/100 mi from the EPA label or fueleconomy.gov (or the WLTP kWh/100 km in kilometer mode). Those figures are measured at the wall and already include charging losses, so efficiency isn't applied again. A trip-computer figure leaves the losses out and is typically 10–25% lower: add that margin if it's the only number you have.
- Time-of-use tariffs: enter the rate for the hours you actually charge. An overnight rate can change the result more than any other input.
How this is calculated
Energy added to the battery is the battery capacity times the gap between the target and starting charge. Because some energy is lost as heat in the charger and battery, the energy you pay for is the energy added divided by the charging efficiency. The U.S. Department of Energy and ADAC both express losses as a share of the energy drawn from the wall, which is what this division does. The cost of the charge is that grid energy times your price per kWh. Cost per 100 miles (or 100 km) is the rated consumption times the price. EPA figures are measured from the charge source and WLTP figures include charging losses, so losses aren't added a second time. The calculator never pulls live electricity prices; enter the rate in whatever currency you pay.
Common questions
Why does it divide by efficiency instead of adding 10%?
Charging losses are measured as a share of the energy taken from the grid, so 90% efficiency means 1 kWh in the battery needs 1 / 0.9 ≈ 1.11 kWh from the wall, not 1.10. The difference is only about 1%, but dividing matches how DOE and ADAC define the loss.
What efficiency should I enter?
If you don't know, keep 90%: the U.S. DOE's FuelEconomy.gov puts typical charging efficiency at 84–93%. ADAC's 2026 tests found 93–95% at an 11 kW wallbox and as low as 76% from a household socket at low current. DC fast charging loses 5–15%, more in cold weather when the battery is heated.
Why doesn't charging efficiency change the cost per 100 miles?
Because the rated kWh/100 mi on the EPA label is already measured from the wall: FuelEconomy.gov states that electricity use is measured from the charge source, and WLTP figures include charging losses too. Dividing by efficiency again would count the losses twice. If you use the trip-computer number instead, add 10–25% (ADAC's measured gap) yourself.
What does the miles/kilometers switch do?
It changes the unit the calculator expects for consumption (kWh/100 mi or kWh/100 km) and the distance the cost is shown for. It doesn't convert a number you've already entered, so retype the consumption after switching. The cost of a charge doesn't depend on units at all.
Part of Automotive Calculators