Preliminary numbers for estimating and for checking a quote. The charger's rating label and installation manual, and the local authority having jurisdiction, come first. A licensed electrician sizes and installs the circuit.

Maintained by BuildSolver · Updated October 22, 2026

Calculator · Electrical

EV charger breaker size calculator

An EV charger is a continuous load, so the breaker and the wire are sized at 125 percent of its current. A 48 A charger on 240 V is 60.00 A, so the breaker is 60 A. In conduit that takes 6 AWG copper THHN on 75°C (167°F) terminals, and NM-B cable (Romex) takes 4 AWG, because NM-B is held to the 60°C (140°F) column. This page gives the breaker and the wire for any charger from 12 to 80 A, and the charger setting a given breaker supports. It does not work the length of the run; the voltage drop calculator does.

Enter the maximum output current from the charger's rating label, or its kW and the supply voltage. If the charger is adjustable, enter the setting you will use.
To check an existing circuit or a quote, enter the breaker on it now. Leave it blank to size a new circuit.
The result shows the smallest breaker at 125 percent, the copper and aluminum wire for NM-B cable and for THHN in conduit, and the charger setting the breaker supports.

One Level 2 EV charger on its own circuit, single phase at 208 or 240 V, 12 to 80 A. The charger manual comes first, and a licensed electrician installs the circuit.

Charger rating is given in

Amps is the better entry. A charger delivers a set current, and the amps on the label or in the app set the breaker. A kW figure is usually rounded.

Charger maximum output, A

The maximum output current on the charger's rating label, or the setting you will use if the charger is adjustable. A Tesla Wall Connector tops out at 48 A, many other home chargers at 32, 40 or 48 A.

Supply voltage

240 V in most houses. Many apartment and commercial buildings are 208 V.

Breaker on the circuit now, A (optional)

To check an existing circuit or a quote, such as a dryer or range circuit. Leave blank to size a new one.

Example result for the default inputs

EV charger at 48 A, 240 V single phase (11.52 kW), on its own circuit. NEC 625.41 and 625.42.

Charger current

48 A

Smallest breaker

60 A

Copper, THHN / NM-B

6 / 4 AWG

Calculation details
Current	48 A x 240 V = 11.52 kW
125 percent, continuous load	1.25 x 48 A = 60.00 A. An EVSE is a continuous load (625.42), and the breaker (625.41) and the conductors are sized at no less than this.
Smallest breaker	60 A, the smallest standard size at or above 60.00 A (Table 240.6(A)).
Wire on 60 A	copper 4 AWG NM-B cable (60°C, 140°F column) or 6 AWG THHN or THWN in conduit (75°C, 167°F column); aluminum 3 AWG on the 60°C (140°F) column or 4 AWG on the 75°C (167°F) column. At 86°F with two current-carrying conductors and 90°C (194°F) insulation. NM-B cable (Romex) is held to the 60°C (140°F) column (334.80); THHN or THWN in conduit can use the 75°C (167°F) column when the terminals on the charger and the breaker are marked for 75°C (167°F). NM cable is not permitted in wet or damp locations (334.12, read in the 2017 text). Unless 240.4(E) or (G) says otherwise, 240.4(D) caps a breaker on small conductors: 15 A on 14 AWG copper, 20 A on 12 AWG and 30 A on 10 AWG.
Charger setting for this breaker	A 60 A breaker supports a charger setting up to 48 A (60 / 1.25, the 80 percent that charger makers print).
Own circuit	The charger goes on its own individual branch circuit (625.40), with no other outlets on it.
GFCI	625.54 asks for GFCI protection of a receptacle that a charger plugs into (as restated for the 2023 edition). Outdoors at a dwelling, 210.8(F) also asks for GFCI protection of outdoor outlets on circuits of 150 V to ground or less and 50 A or less (60 A in the 2026 edition, as EC&M reports). UL's Code Authority reads 210.8(F) as reaching hard-wired equipment, writing of outdoor HVAC, because an outlet is any point where current is taken to supply equipment. Read the same way, a hardwired charger outdoors on such a circuit is covered, though UL does not name chargers and some electricians read them differently. Tesla says the Gen 3 Wall Connector has GFCI protection built in and not to add a GFCI breaker. The Tesla manual lists that protection as CCID20, a 20 mA device, not the 5 mA GFCI that 210.8 asks for, which is where installers and inspectors part ways. Settle it with the AHJ before buying the breaker.
Voltage drop	Not worked here. A long run from the panel may need a larger wire than the ampacity gives. The voltage drop calculator takes the length.

Many chargers accept copper only. The Tesla Gen 3 Wall Connector manual says copper wire terminations only. Check the charger manual before pulling aluminum, and use terminals on the breaker and the charger that are identified for aluminum (110.14).

For estimation purposes only. Consult a licensed engineer for final designs.

Get this result as a PDF, free account

Check the voltage drop on the run

Free without signup

How the breaker, the wire and the setting are worked

An EV charger is treated as a continuous load. The NEC sizes its breaker and its conductors at no less than 125 percent of the charger's current, then the conductor is read from the 60°C (140°F) column for NM-B cable or the 75°C (167°F) column for THHN or THWN in conduit. Run the other way, the same rule gives the highest charger setting a breaker supports: the breaker divided by 1.25.

Charger current: I = amps, or I = kW x 1,000 / VThe maximum output on the charger's label. A kW figure is divided by the supply voltage. A 48 A charger at 240 V makes 11.52 kW, which Tesla prints as 11.5 kW. This page uses the label, because the breaker follows the current.
Smallest breaker: smallest standard size at or above 1.25 x INEC 625.41 sets the overcurrent device at no less than 125 percent of the EVSE current rating, and 625.42 makes the EVSE a continuous load. For 48 A that is 60.00 A, so 60 A. A 50 A charger needs 62.50 A, which rounds up to 70 A. Standard sizes are from NEC Table 240.6(A).
Conductor ampacity: at least 1.25 x I, in the column the terminals and cable allowThe conductor carries the same 125 percent, 60.00 A for a 48 A charger. Table 310.16 gives 6 AWG copper 55 A at 60°C (140°F) and 65 A at 75°C (167°F), so a 48 A charger takes copper 4 AWG NM-B cable (60°C, 140°F column) or 6 AWG THHN or THWN in conduit (75°C, 167°F column). NM-B cable stays in the 60°C (140°F) column (334.80).
Small conductors: breaker no larger than the 240.4(D) limit for the wireUnless 240.4(E) or (G) says otherwise, 240.4(D) caps a breaker on 14 AWG copper at 15 A, 12 AWG at 20 A and 10 AWG at 30 A. A 24 A charger takes a 30 A breaker and 10 AWG copper, and 30 A is the most 240.4(D) allows on 10 AWG.
Setting for a breaker: setting = breaker / 1.25The 125 percent rule run backward is the 80 percent that charger makers print. A 60 A breaker supports 48 A, a 50 A breaker 40 A and a 40 A breaker 32 A.

Eight chargers through the same formula

The 48, 40, 32, 24, 16 and 12 A rows are the output settings in the Tesla Gen 3 Wall Connector manual, and the page gives the same breakers: 60, 50, 40, 30, 20 and 15 A. ChargePoint tops its Home Flex out at the 50 A row and pairs it with 70 or 80 A. Power is current times 240 V; Tesla prints it cut to one decimal, 7.6 kW for the 32 A row where the exact figure is 7.68 kW.

Current, power, smallest breaker and copper wire for eight EV chargers
Charger	kW at 240 V	Smallest breaker, A	Copper NM-B, 60°C (140°F), AWG	Copper THHN, 75°C (167°F), AWG
48 A (Tesla Wall Connector maximum)	11.52	60	4	6
40 A	9.60	50	6	8
32 A	7.68	40	8	8
24 A	5.76	30	10	10
16 A	3.84	20	12	12
12 A	2.88	15	14	14
50 A (ChargePoint Home Flex maximum)	12.00	70	4	6
80 A	19.20	100	1	3

Wire is for 86°F, two current-carrying conductors and 90°C (194°F) insulation. THHN in the 75°C (167°F) column needs terminals on the charger and the breaker marked for 75°C (167°F). A 48 A charger splits the columns: 6 AWG THHN works, and 4 AWG is the NM-B size.

Charger setting a breaker supports

Run backward, the 125 percent rule gives the highest charger setting a breaker supports, the breaker divided by 1.25. That is the 80 percent Tesla and ChargePoint print. Wire on the circuit still has to be rated for the breaker.

Highest charger setting for each common breaker size
Breaker, A	Highest charger setting, A	kW at 240 V
15	12	2.88
20	16	3.84
30	24	5.76
40	32	7.68
50	40	9.60
60	48	11.52
70	56	13.44
80	64	15.36
100	80	19.20

Standards and data sources

NEC 2023, 625.40, 625.41, 625.42, 625.43, 625.54, Table 310.16, Table 240.6(A), 240.4(D) and 334.80 - the individual branch circuit, the 125 percent breaker and conductor rule for an EVSE, the continuous-load rule, the disconnect above 60 A, GFCI for receptacles, the conductor ampacity columns and the small-conductor limits. The NEC text was read as Mike Holt Enterprises and the Electrical Training Alliance print it, not in NFPA's viewer.
Mike Holt Enterprises, Understanding 2023 NEC Requirements for Solar PV and Energy Storage Systems, Article 625 - the 2023 wording of 625.40 to 625.43 and 625.54, and the worked example this page checks against: a 40 A EVSE needs a 50 A breaker, 8 AWG at 75°C (167°F) or 6 AWG NM-B cable at 60°C (140°F).
Electrical Training Alliance reference on the 2017 National Electrical Code, EV charging - the 2017 edition's 125 percent rule for the breaker and the EVSE as a continuous load, which this page follows in 2023 numbering.
John Lupacchino in EC&M, Code Quiz on GFCI protection of outdoor outlets (2026) - 210.8(F): outdoor outlets at dwelling units on circuits of 150 V to ground or less need GFCI protection, up to 60 A in the 2026 edition, raised from 50 A.
Tesla, Gen 3 Wall Connector Installation Manual - the six breaker and maximum output pairs the page is tested against, 60 A and 48 A down to 15 A and 12 A, the 6 AWG copper minimum at full power, copper-only terminals and the built-in ground-fault protection.
ChargePoint, Home Flex installation FAQ - the amperage setting and breaker table, 16 A on 20 A up to 48 A on 60 A and 50 A on 70 or 80 A, and the 80 percent of breaker rating.

Limitations of this calculator

This page gives preliminary numbers for estimating and for checking a quote. A licensed electrician sizes and installs the circuit under the permit and the inspection of the local authority having jurisdiction (AHJ). Nothing here is an approval of an installation.
The charger's rating label and installation manual come first. A maker can require a larger wire, a particular breaker or a 90°C (194°F) copper conductor, and listed equipment is installed according to its listing.
The NEC text was read as Mike Holt Enterprises (2023 edition) and the Electrical Training Alliance (2017 edition) restate it, not in NFPA's own viewer. Section numbers and wording moved between editions, and the 2020 text was not opened. Check the edition and the local amendments your AHJ uses.
Chargers with adjustable settings or load management: the numbers are for the current you enter. With an energy management system, the 2023 text as commentaries quote it sizes the service and feeder for the most the system lets the charger draw, not for its full rating (625.42(A), 750.30); Mike Holt's restatement words this as the charger load not being included. 625.42(B) asks for the adjustable setting on the rating label and, as quoted, lets a charger whose ampere adjustment has restricted access be rated at the setting. Electricians read differently whether that setting may size the branch circuit, so ask the AHJ, and a later increase of the setting needs wire and a breaker for the new current.
Wire sizes are for copper and aluminum at 86°F with two current-carrying conductors and 90°C (194°F) insulation. NM-B cable (Romex) is held to the 60°C (140°F) column and is not allowed in wet or damp locations (334.12, read in the 2017 text). A hot attic, more conductors in a conduit and a long run change the size.
Voltage drop is not worked. Use the voltage drop calculator for the length of the run, and the conduit fill calculator for the conduit.
The page works one Level 2 charger on its own circuit, single phase at 208 or 240 V, from 12 to 80 A. A 120 V Level 1 cord-and-plug unit, three phase chargers and DC fast chargers are not covered.
A charger rated more than 60 A needs a disconnecting means (625.43, as restated for 2023). A charger that plugs into a receptacle needs GFCI protection of the receptacle (625.54, as restated for 2023); the receptacle, its rating and the cord are set by the charger manual and the AHJ. Outdoors at a dwelling, 210.8(F) also covers outdoor outlets on circuits of 50 A or less (60 A in the 2026 edition, as EC&M reports). UL's Code Authority reads 210.8(F) as reaching hard-wired equipment, writing of outdoor HVAC, because an outlet is any point where current is taken to supply equipment. Read the same way, a hardwired charger outdoors on such a circuit is covered, though UL does not name chargers and some electricians read them differently; the AHJ settles it.
The page does not size the service or the feeder. The charger's share of the load calculation (220.57) is a separate step, and an electrician checks the panel before a charger goes on it.

Common mistakes with EV charger circuits

6 AWG Romex on a 60 A breaker for a 48 A charger. A 48 A charger is 60.00 A of conductor at 125 percent. 6 AWG NM-B cable is 55 A in the 60°C (140°F) column, so it falls short and NM-B needs 4 AWG. 6 AWG THHN or THWN in conduit is 65 A at 75°C (167°F) and carries it when the terminals are marked 75°C (167°F). How a local inspector reads NM cable on this load varies, so ask before you buy cable.
Putting a 48 A charger on a 50 A breaker. A 48 A charger needs a 60 A breaker. A 50 A breaker supports a setting of 40 A, so it is too small for 48 A. Turn the charger down to 40 A, or change the breaker and the wire.
Sizing the wire for the charger amps instead of 125 percent. A 40 A charger needs 50.00 A of conductor and a 50 A breaker. 8 AWG NM-B carries 40 A at 60°C (140°F), which is the charger current but not the 125 percent, so the NM-B size is 6 AWG. The same 40 A on THHN at 75°C (167°F) takes 8 AWG.
Choosing the GFCI question last. Tesla's Gen 3 Wall Connector manual says its GFCI protection is built in and not to install a GFCI breaker. The Tesla manual lists that protection as CCID20, a 20 mA device, not the 5 mA GFCI that 210.8 asks for, which is where installers and inspectors part ways. 625.54 asks for GFCI on a receptacle a charger plugs into, and 210.8(F) covers outdoor outlets at a dwelling on circuits of 50 A or less (60 A in the 2026 edition, as EC&M reports). UL's Code Authority reads 210.8(F) as reaching hard-wired equipment, writing of outdoor HVAC, because an outlet is any point where current is taken to supply equipment. Read the same way, a hardwired charger outdoors on such a circuit is covered, though UL does not name chargers and some electricians read them differently. On that reading a 40 A charger on a 50 A breaker outdoors would fall under it in the 2023 edition, and a 48 A charger on 60 A in the 2026 edition. Ask the AHJ before the breaker is bought.
Two chargers on one circuit. A charger is on its own individual branch circuit (625.40). The 2023 text, as restated, allows one circuit to feed more than one charger only when an energy management system controls the loads. Without one, each charger gets its own breaker and wire; the Tesla manual says the same for sites with several Wall Connectors.
Reading the breaker off a rounded kW figure. A label of 7.7 kW at 240 V is 32.08 A, and 125 percent of it lands on a 45 A breaker. The charger behind it is a 32 A unit that needs 40 A. Use the amps from the label or the app when you have them. 11.5 kW is 47.92 A and still rounds to 60 A.

Common questions about EV charger breakers

What size breaker do I need for a 48 amp EV charger?

60 A. An EV charger is a continuous load, so the breaker is at least 125 percent of the charger's current: 1.25 x 48 A = 60.00 A, and 60 A is the standard size. Tesla's table for the Gen 3 Wall Connector shows the same, a 60 A breaker for 48 A output.

What wire size for a 48 amp EV charger?

The conductors need 60.00 A of ampacity. In conduit with THHN or THWN and 75°C (167°F) terminals that is 6 AWG copper (65 A). NM-B cable (Romex) is held to the 60°C (140°F) column, where 6 AWG is only 55 A, so it takes 4 AWG copper. Tesla's manual asks for at least 6 AWG, 90°C (194°F) rated copper at full power, and says to upsize if needed. Add voltage drop for a long run.

Can I use Romex (NM-B) for an EV charger?

Yes, indoors in a dry location, if the cable is sized from the 60°C (140°F) column. A 40 A charger takes 6 AWG NM-B on a 50 A breaker, and a 48 A charger takes 4 AWG on 60 A. NM cable is not allowed in wet or damp locations, so an outdoor or garage-wall run usually goes in conduit with THWN wire. Local rules vary.

Is an EV charger a continuous load?

Yes. The 2023 NEC, as restated by Mike Holt Enterprises, says an electric vehicle supply equipment is considered a continuous load (625.42), and the overcurrent protection is at least 125 percent of its current rating (625.41). The 2017 text, as restated by the Electrical Training Alliance, also treats it as a continuous load at 125 percent. Section numbers moved between editions.

What breaker does a 40 amp, 32 amp or 24 amp charger need?

A 40 A charger needs 50 A, a 32 A charger 40 A, a 24 A charger 30 A, a 16 A charger 20 A and a 12 A charger 15 A. In the other direction, Tesla pairs 60, 50, 40, 30, 20 and 15 A breakers with 48, 40, 32, 24, 16 and 12 A of output.

Can I set the charger lower than the breaker allows?

Yes. That is how the maker tables work. A 60 A breaker supports up to 48 A, a 50 A breaker 40 A and a 40 A breaker 32 A. ChargePoint tells drivers they can adjust charging to 80 percent of the breaker amperage or the charger's maximum rating. The wire must still be rated for the breaker, so a bigger breaker than 125 percent needs bigger wire.

Do I need a GFCI breaker for an EV charger?

It depends on the location and the edition. The 2023 NEC, as restated, asks for GFCI protection of a receptacle that connects a charger (625.54). Outdoors at a dwelling, 210.8(F) asks for GFCI protection of outdoor outlets on circuits of 150 V to ground or less and 50 A or less, raised to 60 A in the 2026 edition as EC&M reports. UL's Code Authority reads 210.8(F) as reaching hard-wired equipment, writing of outdoor HVAC, because an outlet is any point where current is taken to supply equipment. Read the same way, a hardwired charger outdoors on such a circuit is covered, though UL does not name chargers and some electricians read them differently. Tesla says the Gen 3 Wall Connector includes integrated GFCI protection and not to install a GFCI breaker. The Tesla manual lists that protection as CCID20, a 20 mA device, not the 5 mA GFCI that 210.8 asks for, which is where installers and inspectors part ways. Ask your inspector before buying the breaker.

Does an EV charger need a disconnect?

The 2023 NEC, as restated by Mike Holt Enterprises, asks for a readily accessible disconnecting means for an EVSE rated more than 60 A (625.43). A 48 A charger is under that. Tesla's manual calls external disconnect switches neither required nor recommended for its unit, with the breaker as the means of disconnect. A charger of 61 A to 80 A, such as an 80 A unit on 100 A, needs one.

What about a 120 volt Level 1 charger?

This page does not size 120 V Level 1 units. It works 208 and 240 V single-phase chargers from 12 to 80 A. For a plug-in Level 1 unit, the outlet, its circuit and its protection are set by the charger manual and the AHJ.

Does this replace an electrician?

No. This page is for estimating and for checking numbers on a quote. A licensed electrician sizes and installs the circuit under a permit, and the local authority having jurisdiction inspects it.