The EV charging cost calculator estimates grid energy and cost required to add a specified amount of energy to an electric vehicle battery. Charging efficiency accounts for energy lost between the outlet and battery.
How to use this calculator
Enter the kilowatt-hours you want to add, electricity price per kWh, and charging efficiency. A lower efficiency means more grid energy is required for the same battery energy. The model does not require battery capacity.
Formula & calculation method
Grid energy = battery energy added / (efficiency/100); cost = grid energy × electricity priceBattery energy is the useful energy stored, while grid energy is what the electricity supply must deliver. The difference is an estimated charging loss. Efficiency of 100% means no loss in this simplified model.
Worked example
Adding 40 kWh at 90% efficiency requires about 44.44 kWh from the grid. At 0.20 per kWh, the estimated cost is 8.89, with about 4.44 kWh attributed to loss.
Why this is useful
Separating battery energy, grid energy, and losses clarifies why cost cannot always be calculated by multiplying battery capacity by the tariff alone. Efficiency is user-adjustable for different charging setups.
Limitations to keep in mind
Efficiency varies with charger, vehicle, temperature, power level, and battery state. Public charging may add session fees, idle fees, taxes, or subscription pricing that are not included unless reflected in your entered rate.
Frequently asked questions
Should I enter full battery capacity?
Only if you intend to add that entire capacity. For a partial charge, enter the energy to be added, such as from current to target charge.
What efficiency should I use?
Use a vehicle or charger estimate if available. Otherwise, test scenarios rather than treating any single value as guaranteed.
Does cost include public charging fees?
Only when they are already included in your effective per-kWh price. Fixed session or idle fees must be added separately.