Battery & energy
EV Charging Cost Calculator
EV charging cost equals grid energy multiplied by your electricity rate. Grid energy accounts for battery capacity, charge-level change, and charging efficiency.
Estimate EV charging energy, time, and cost from battery capacity, charge change, efficiency, charger power, and your rate.
Calculated result
Estimated charging cost
Calculating…
Calculated locally in your browser
Planning math only. Verify equipment specifications and installation requirements separately.
What this calculator returns
Actual charging power tapers and vehicle or charger limits can lengthen the session.
Formula and variables
The calculation runs entirely in your browser. Static formulas, definitions, examples, and tables remain readable without JavaScript.
Grid kWh = battery capacity x charge-level change / efficiency; cost = grid kWh x rate; time = grid kWh / charger kW.
- W
- Average real power in watts.
- h
- Operating or charging time in hours.
- kWh
- Accumulated electrical energy in kilowatt-hours.
- rate
- User-entered electricity price per kilowatt-hour.
- η
- User-entered efficiency expressed as a decimal or percentage.
Charge levels and efficiency are percentages; charger power is the average grid-side power used for the time estimate.
Worked example
| Input | Value |
|---|---|
| Battery capacity | 75 kWh |
| Starting charge | 20 % |
| Target charge | 80 % |
| Charger power | 7.2 kW |
Charging a 75 kWh battery from 20% to 80% at 90% efficiency draws about 50 kWh and costs $7.50 at $0.15/kWh.
Reference table
| Use case | Energy | At $0.15/kWh | At $0.30/kWh |
|---|---|---|---|
| 1 kW for 1 hour | 1 kWh | $0.15 | $0.30 |
| 1.5 kW for 4 hours | 6 kWh | $0.90 | $1.80 |
| 30 kWh EV session | 30 kWh | $4.50 | $9.00 |
| 900 kWh billing period | 900 kWh | $135.00 | $270.00 |
Frequently asked questions
Why use wall energy instead of battery energy?
Charging losses mean energy drawn from the outlet can exceed energy added to the battery, so cost is based on wall energy.
Does the result include charging time?
Yes, from entered charger power, but real vehicles may taper charging or limit power under some conditions.
Why is grid energy higher than battery energy?
Charging losses mean the grid must supply more energy than the battery stores; the entered efficiency represents that difference.
Assumptions and limitations
- No station fee, idle fee, tax, thermal taper, auxiliary load, or utility-rate database.
- Battery capacity and efficiency are user assumptions.
Method and sources
Review the electrical formulas, calculation methodology, and standards status for the references most relevant to this calculation. The broader technical sources index records source scope and verification. Last reviewed .