How to estimate home EV charging cost

Begin with energy added

A session from 30% to 80% does not add the battery's full nameplate capacity. Use the energy added from the vehicle or charger record when available. Repeated sessions can then be summed for the billing period.

Account for charging losses

Wall energy is higher than energy stored in the battery. Divide battery energy added by the wall-to-battery efficiency. Temperature, battery conditioning, charger power and low-current charging can change the loss.

Match the tariff time

If charging occurs overnight, use the applicable off-peak rate only when the plan and meter define that period. Add a plan comparison separately if changing tariff also changes the standing charge or peak price.

Avoid false fuel comparisons

Cost per distance depends on the distance driven from the charged energy. It does not include public charging, subscription fees, tyre wear, vehicle purchase, insurance or battery depreciation.

For a fair before-and-after check, use distance and wall energy covering the same dates. A single short session may include unusual conditioning energy, while a monthly total usually gives a more representative home-charging picture.