Recommend the breaker and circuit size for an EV charger continuous load.
Charge speed by current
Panel load
Usage Tip
Match the wire gauge to the breaker, and confirm your panel has room for a double-pole 240 V breaker before buying the charger.
breaker = round up( charger amps ÷ 0.8 )
The result rounds up to the next standard breaker size.
What breaker and wire does an EV charger need?
EV charging is a continuous load — it runs for hours — so the NEC requires the circuit to be sized at 125 percent of the charger's current. A 48A charger therefore needs a 60A breaker, and the wire has to match that breaker. The other half of the question is whether your panel can carry the extra load on top of the house. This calculator does all of it: the breaker, the wire, the charging speed, and the impact on your panel, so you know whether you can charge overnight without rewiring half the house.
The NEC 125% continuous load rule
Because the charger runs continuously, the breaker and wire are sized to 125 percent of the charging current, then rounded up to the next standard breaker:
| Charger | x 1.25 | Breaker |
|---|---|---|
| 16A | 20A | 20A |
| 24A | 30A | 30A |
| 32A | 40A | 40A |
| 40A | 50A | 50A |
| 48A | 60A | 60A |
| 60A | 75A | 80A |
Wire size by breaker
Typical copper (THHN, 75°C) for each breaker. Long runs or aluminum need upsizing for voltage drop:
| Breaker | Copper wire |
|---|---|
| 20A | 12 AWG |
| 30A | 10 AWG |
| 40A | 8 AWG |
| 50A | 6 AWG |
| 60A | 6 AWG (4 AWG for long runs) |
| 80A | 4 AWG |
EV charging speed comparison
Range added per hour depends on the power (volts times amps) and the vehicle's efficiency, roughly 3 to 4 miles per kWh:
| Charger | Typical speed |
|---|---|
| Level 1 (120V, 12A) | 3 to 5 mi/hr |
| 16A Level 2 (240V) | 10 to 15 mi/hr |
| 32A Level 2 | 20 to 30 mi/hr |
| 48A Level 2 | 30 to 40 mi/hr |
Panel capacity explained
Your service panel has a total amperage, and the EV charger adds to whatever the house already draws:
| Panel | EV charging headroom |
|---|---|
| 100A | Often tight — may need load management or an upgrade |
| 125A | Usually fine for a 32A charger |
| 200A | Comfortably handles a 48A charger in most homes |
A load-management device (a smart splitter or breaker that pauses charging when the house demand is high) can let you add a charger without upgrading the service.
Load calculation example
Add the home's peak demand to the charger's continuous draw to see the impact:
| Item | Load |
|---|---|
| Existing house load | 85A |
| EV charger (48A) | 48A |
| Total | 133A |
On a 200A panel that is about 67 percent — comfortable. On a 100A panel the same charger would push past the limit. A proper service load calculation per NEC 220 confirms it.
Hardwired vs plug-in
Plug-in chargers use a receptacle, most commonly a NEMA 14-50 on a 50A circuit, which limits the charger to 40A continuous. They are flexible and easy to replace. Hardwired chargers connect directly to the circuit and can run higher — 48A on a 60A circuit, or more — and are required outdoors in some areas and for anything above a 50A circuit. If you want the full 48A or 60A, hardwire it.
Frequently asked questions
What size breaker for a 48A EV charger?
A 60A breaker. The charger is a continuous load, so the circuit is sized at 125 percent (48 x 1.25 = 60).
What wire for a 50A EV charger circuit?
6 AWG copper for a 50A circuit; step up to 4 AWG for long runs or to limit voltage drop.
How fast does a Level 2 charger add range?
Roughly 20 to 30 miles per hour at 32A, and 30 to 40 at 48A, depending on the vehicle.
Can a 100A panel handle an EV charger?
Sometimes, with a smaller charger or a load-management device. A full 48A charger often needs a 200A panel or a load manager.
Do I need to hardwire my charger?
For 48A or higher you must hardwire. Up to 40A you can use a NEMA 14-50 plug on a 50A circuit.
Should I install a bigger charger than I need now?
Often yes. Running the wire and breaker for 48A while the walls are open is cheap insurance for a future vehicle, even if today's car only takes 32A.
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Estimates are for planning and education, not a substitute for the NEC or a licensed electrician. EV circuits require a permit and inspection in most areas, a proper NEC 220 service load calculation, and consideration of voltage drop, ambient temperature and continuous-duty derating. Have the work designed and installed by a professional.