How many amps can 12 gauge wire carry?

12 AWG copper is 20 A at 60°C, 25 A at 75°C and 30 A at 90°C in Table E3705.1, but E3705.5.3 limits its breaker to 20 A. For a household circuit, 12 AWG copper is a 20 A wire.

How many amps can 10 gauge wire carry?

10 AWG copper is 30, 35 and 40 A in the three columns, and E3705.5.3 caps its breaker at 30 A. 10 AWG aluminum is 25, 30 and 35 A, capped at 25 A.

What size wire for 50 amps?

8 AWG copper at 75°C (50 A) where the terminals are rated 75°C, or 6 AWG copper at 60°C (55 A). In aluminum, 6 AWG at 75°C (50 A).

What size wire for 100 amps?

3 AWG copper at 75°C (100 A) or 1 AWG aluminum at 75°C (100 A) as a branch or feeder. A dwelling service or main feeder can use a smaller size under Table E3603.1.1, which the wire size calculator explains.

Is Table E3705.1 the same as NEC 310.16?

It carries NEC Table 310.16's values, reprinted in the residential code for one and two family dwellings with the NEC section cited in brackets. It is the free, public version of the same numbers.

How do I derate wire for more conductors?

Multiply the table value by 80% for 4 to 6 current-carrying conductors, 70% for 7 to 9, 50% for 10 to 20, 45% for 21 to 30, 40% for 31 to 40 and 35% above that, from Table E3705.3.

Home › Electrical › Wire Ampacity Chart

Wire Ampacity Chart

IRC Table E3705.1, the residential reprint of NEC Table 310.16

The ampacity chart everybody looks up is NEC Table 310.16, which sits behind NFPA's login. The residential code prints the same values for dwellings as Table E3705.1, with the NEC section in brackets, and that is the chart below: every size from 14 AWG to 900 kcmil, copper and aluminum, at 60, 75 and 90°C. Pick a size and the calculator reads the row, applies the ambient and bundling factors, and gives the breaker limit the table leaves out.

Look up a wire

Wire size

Conductor

Insulation column

Ambient temperature

Current-carrying conductors in the raceway or cable

no.

Enter how many conductors in the raceway or cable carry current; Table E3705.3 sets the factor.

Specification summary

Generated from on . Reopen that address to reproduce these figures exactly.

Entered

Result

Worked example

12 AWG THHN copper, three conductors, at a normal room temperature.

Table E3705.1. 12 AWG copper reads 20 A at 60°C, 25 A at 75°C and 30 A at 90°C.
Breaker limit. E3705.5.3 caps 12 AWG copper at 20 A whatever the column says.

The 30 A in the 90°C column is real, and it is for derating from, not for sizing the breaker.

The formula

Read the row, then apply the two factors the code prints beside it:

adjusted ampacity = Table E3705.1 value × ambient factor (E3705.2) × bundling factor (E3705.3)

ambient factor: 1.00 at 78 to 86°F, lower in a hot attic
bundling factor: 80% for 4 to 6 current-carrying conductors, 70% for 7 to 9, 50% for 10 to 20

Then the breaker is limited by E3705.5.3 for 14, 12 and 10 AWG copper and 12, 10 and 8 AWG aluminum.

Where the numbers come from

The chart is IRC 2021 Table E3705.1, read from the Utah Residential Code and confirmed identical in Virginia's adoption. It carries NEC Table 310.16's values for the conductors used in dwellings, and the correction and adjustment tables are E3705.2 and E3705.3.

Every cell was checked to rise with wire size and with the temperature column. None fails.

The chart: ampacity by wire size

IRC Table E3705.1 (NEC 310.16 values), amperes, not more than three current-carrying conductors, 86°F ambient
Size	Copper 60°C	Copper 75°C	Copper 90°C	Aluminum 60°C	Aluminum 75°C	Aluminum 90°C
14 AWG	15	20	25	-	-	-
12 AWG	20	25	30	15	20	25
10 AWG	30	35	40	25	30	35
8 AWG	40	50	55	35	40	45
6 AWG	55	65	75	40	50	55
4 AWG	70	85	95	55	65	75
3 AWG	85	100	115	65	75	85
2 AWG	95	115	130	75	90	100
1 AWG	110	130	145	85	100	115
1/0 AWG	125	150	170	100	120	135
2/0 AWG	145	175	195	115	135	150
3/0 AWG	165	200	225	130	155	175
4/0 AWG	195	230	260	150	180	205
250 kcmil	215	255	290	170	205	230
300 kcmil	240	285	320	195	230	260
350 kcmil	260	310	350	210	250	280
400 kcmil	280	335	380	225	270	305
500 kcmil	320	380	430	260	310	350
600 kcmil	350	420	475	285	340	385
700 kcmil	385	460	520	315	375	425
750 kcmil	400	475	535	320	385	435
800 kcmil	410	490	555	330	395	445
900 kcmil	435	520	585	355	425	480

A dash means the table lists no ampacity: aluminum starts at 12 AWG.

What size wire for each breaker

The chart answers "how many amps can this wire carry". The question most people start from is the reverse. Reading it backwards, with the small-conductor limits applied:

Smallest wire from Table E3705.1 with E3705.5.3 applied, normal ambient, three or fewer conductors
Breaker	Copper at 60°C	Copper at 75°C	Aluminum at 75°C
15 A	14 AWG	14 AWG	12 AWG
20 A	12 AWG	12 AWG	10 AWG
30 A	10 AWG	10 AWG	8 AWG
40 A	8 AWG	8 AWG	6 AWG
50 A	6 AWG	8 AWG	6 AWG
60 A	4 AWG	6 AWG	4 AWG
70 A	4 AWG	4 AWG	3 AWG
100 A	1 AWG	3 AWG	1 AWG
125 A	1/0 AWG	1 AWG	2/0 AWG
150 A	3/0 AWG	1/0 AWG	3/0 AWG
200 A	250 kcmil	3/0 AWG	250 kcmil

The 60°C column is the one for ordinary household circuits of 100 A or less, because that is the rating the code assumes for their terminals. A 20 A aluminum circuit needs 10 AWG, not 12: the table gives 12 AWG aluminum 20 A at 75°C, but E3705.5.3 caps it at 15 A.

Why three columns, and which one to read

The three columns are the insulation's temperature rating, not three grades of copper. A wire can carry more current if its insulation tolerates more heat, so the 90°C column is always the largest.

The code lets you start from the 90°C figure when you derate for a hot space or a full raceway, and then requires the result to be no more than the terminal column allows. That is why 12 AWG THHN shows 30 A and is still a 20 A wire in a house.

Frequently asked questions

How many amps can 12 gauge wire carry?: 12 AWG copper is 20 A at 60°C, 25 A at 75°C and 30 A at 90°C in Table E3705.1, but E3705.5.3 limits its breaker to 20 A. For a household circuit, 12 AWG copper is a 20 A wire.
How many amps can 10 gauge wire carry?: 10 AWG copper is 30, 35 and 40 A in the three columns, and E3705.5.3 caps its breaker at 30 A. 10 AWG aluminum is 25, 30 and 35 A, capped at 25 A.
What size wire for 50 amps?: 8 AWG copper at 75°C (50 A) where the terminals are rated 75°C, or 6 AWG copper at 60°C (55 A). In aluminum, 6 AWG at 75°C (50 A).
What size wire for 100 amps?: 3 AWG copper at 75°C (100 A) or 1 AWG aluminum at 75°C (100 A) as a branch or feeder. A dwelling service or main feeder can use a smaller size under Table E3603.1.1, which the wire size calculator explains.
Is Table E3705.1 the same as NEC 310.16?: It carries NEC Table 310.16's values, reprinted in the residential code for one and two family dwellings with the NEC section cited in brackets. It is the free, public version of the same numbers.
How do I derate wire for more conductors?: Multiply the table value by 80% for 4 to 6 current-carrying conductors, 70% for 7 to 9, 50% for 10 to 20, 45% for 21 to 30, 40% for 31 to 40 and 35% above that, from Table E3705.3.

Check these numbers yourself

Utah Residential Code 2021, Chapter 37 Branch Circuit and Feeder RequirementsIRC 2021 as adopted in Utah, read through UpCodes. Tables E3705.1, E3705.2, E3705.3 and Section E3705.5.3, with the NEC sections in brackets. Read 2026-09-13; Virginia's adoption prints the same tables identically.

How every figure here is verified: Sources & Method. Who builds this: Lucas Pradella, and the method is on About. Found something wrong? Tell us and it gets fixed or removed.

Figures on this page last checked against the source documents on 2026-09-30. Codes are amended locally; confirm against the edition your jurisdiction enforces.

Related calculators

Dwelling values from the residential code. Commercial work, other conductor types and conditions outside these tables follow the NEC itself and your inspector.