How EV charging cost is calculated
The cost of charging an electric vehicle depends on how much energy goes into the battery, how efficiently the charger delivers that energy (some is lost as heat), and your electricity rate.
The formula
This calculator finds the energy added to the battery with Energy to Battery = Battery Capacity × Charge Percentage, divides by a charging efficiency factor to estimate Energy Drawn from Wall (since chargers aren’t 100% efficient), then multiplies by your electricity rate: Cost = (Energy to Battery ÷ Efficiency) × Rate.
Actual costs vary with charger type, temperature, time-of-use electricity rates, and vehicle-specific charging curves. This calculator gives a general estimate for budgeting purposes, not an exact utility bill figure.
Last reviewed August 2026