EV Charger Size Calculator

Most drivers are fine with a 32 to 40 A Level 2 charger. Divide your daily miles by your car's miles per kWh, add about 10% for charging loss, and divide by the hours you are home times 0.24 kW per amp. 40 miles a day in a sedan needs only about 12 A over 10 hours, so even a 32 A charger has plenty of headroom.

A 50 A breaker. The National Electrical Code (NEC 625) treats EV charging as a continuous load, so the circuit must be rated 125% of the charger's current: 32 A needs 40 A, 40 A needs 50 A, and 48 A needs 60 A.

Yes, if the charger has a NEMA 14-50 plug and is set to 40 A or less. Use an industrial-grade outlet on its own 50 A circuit, since standard outlets can overheat under hours of steady load. A 48 A charger must be hardwired.

Only get 48 A if you drive long days or have a big truck or SUV and short nights. 48 A adds about 20% more range per hour than 40 A, but it needs a 60 A breaker, hardwiring and heavier wire. For 40 to 60 miles a day, 40 A is plenty.

Daily kWh x your rate. A sedan driving 40 miles a day uses about 11.7 kWh, about $2 a day or $61 a month at the US average of 17.3 cents. Time-of-use plans with cheap overnight rates can cut that in half.

About 25 to 40 miles an hour for most cars. A 40 A charger delivers 9.6 kW; at about 3.8 miles per kWh that is about 33 miles an hour, and about 19 miles an hour for a pickup at 2.2 miles per kWh.

For about 30 miles a day or less, often yes. A 120V outlet at 12 A delivers about 1.4 kW, around 4 to 5 miles of range per hour, so 10 hours overnight adds 40 to 50 miles in a sedan. Trucks and longer commutes need Level 2.

Match your car's charge port. Teslas and many 2025 and later models from other makers use NACS; most other EVs through 2025 use J1772. Adapters exist both ways, but a charger with the native plug is simpler and there is nothing to lose.

Hardwired is required for 48 A, often required outdoors by local code, and avoids outlet wear. Plug-in is easier to take with you when you move and can share an existing 14-50 outlet. Both charge at the same speed at the same amps.

Not for charging speed. Wi-Fi helps if your utility has time-of-use rates or rebates that require a connected charger, since you can schedule charging for the cheapest hours. Most cars can also schedule charging on their own.