EV Charging Cost Calculator
Estimate the electricity, cost and time to charge an electric car from one battery percentage to another. Enter your vehicle, charging power and actual electricity rate.
Charging speed changes: An EV may taper power as its battery fills, especially on DC fast chargers. A rated peak power can make this time estimate too short. Use your average measured charger power for a better estimate. Taxes, demand charges and idle fees are outside this estimate unless included in your inputs.
How the EV charging calculation works
Energy stored = usable battery capacity × (target percentage − starting percentage) ÷ 100. Grid energy = energy stored ÷ charging efficiency. Time = grid energy ÷ the lower of entered charger power and any vehicle power limit. Total cost = grid energy × price per kWh + session fee + time × time-based fee.
Checked example
A 75 kWh usable battery charged from 20% to 80% stores 45 kWh. At 90% efficiency it draws 50 kWh from the grid. At an average 7.2 kW, charging takes about 6 hours 57 minutes. At $0.18/kWh and no fees, the estimated cost is $9.00.
What the estimate leaves out
The model assumes a constant average input power and efficiency for the selected interval. Actual energy and elapsed time depend on battery temperature, state of charge, battery management, charger availability, shared power, preconditioning and auxiliary loads. Public stations may bill for minutes, sessions or idle time differently. A home tariff may include taxes, fixed charges and time-of-use rates; enter the effective rate for the hours you plan to charge. This is a planning estimate, not a utility or charging-network quote.
Frequently asked questions
Why is grid energy larger than the battery gain? Charging and vehicle systems use some energy as heat and for supporting loads. The efficiency input represents those losses.
Can I use a 150 kW fast charger? Yes, but enter the average power delivered over the selected charging range. The advertised peak often applies only briefly, so a 150 kW input can substantially understate the time.
Should I use total or usable battery capacity? Use usable capacity when available. If only gross capacity is known, the result may overstate energy gained for a given displayed percentage change.
Related tools: Battery Charging Calculator for current and charge rate, and kW vs kWh for the distinction between power and energy. Compare annual ownership assumptions with the Electric Vehicle Savings Calculator.