How to calculate EV charging cost

Start with the energy you buy

Charging cost is electricity purchased in kilowatt-hours (kWh), multiplied by price per kWh, plus applicable fees. Battery energy gained is not necessarily electricity purchased: some energy is lost during charging.

Formula and example

Battery energy added = usable capacity × (ending charge − starting charge)/100. Purchased energy = battery energy ÷ charging efficiency.

For a 60 kWh usable battery charged from 20% to 80%, the battery gains 36 kWh. At an assumed 90% efficiency, the meter supplies 40 kWh. At 0.25 currency units/kWh, the energy charge is 10 currency units before fees.

Avoid counting losses twice

If your consumption comes from a home electricity meter, it may already include charging losses. Use 100% efficiency in that case. A dashboard consumption figure typically has a different measurement boundary; check the vehicle documentation.

Home versus public charging

Compare the actual tariff and include session, parking, idle or time-based fees. Divide a membership fee across your expected charging sessions if you want an all-in comparison. Peak charging power does not tell you the final cost.

Which tool?

Use EV charging cost for one state-of-charge change, trip and annual electricity cost for driving budgets, and charging time for an average-power estimate.