Have a licensed electrician size and install the circuit. This calculator shows the usual breaker size; your panel, wire run and local code decide the final design.
How it works
- Charging power: charger current × voltage. A 32 A charger at 240 V delivers 7.68 kW.
- Breaker size: EV charging is a continuous load, so the circuit is sized at 125% of the charger current and rounded up to the next standard breaker size. The Department of Energy gives the example of a 30 A charger on a dedicated 40 A circuit under National Electrical Code Article 625 (AFDC).
- Range per hour: charging power ÷ your EV's kWh per 100 miles from its EPA label.
Which current do you need?
Most drivers add their daily miles overnight with any Level 2 charger. A higher current helps if you drive long distances every day or your EV has a large battery, but only if your car's onboard charger accepts that power. A bigger charger also needs a bigger breaker and thicker wire, and may need a panel upgrade.
For a full charge time from your battery level, use the EV charging time calculator.