Wire size and ampacity chart

Base ampacity for insulated conductors rated up to 2,000 V, no more than three current-carrying conductors in a raceway, cable or earth, at 30 °C (86 °F) ambient. Adjust for real conditions before choosing a size.

VC-5 ampacity tableNEC 2023 TABLE 310.16

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Need a size for your exact conditions? Use the wire size calculator, which applies temperature, bundling and voltage drop.

Size	Copper (A)			Aluminum / Cu-clad Al (A)			mm²	Max OCPD 240.4(D)
Size	60 °C	75 °C	90 °C	60 °C	75 °C	90 °C	mm²	Max OCPD 240.4(D)
14 AWG	15	20	25	—	—	—	2.08	Cu 15 A
12 AWG	20	25	30	15	20	25	3.31	Cu 20 A · Al 15 A
10 AWG	30	35	40	25	30	35	5.261	Cu 30 A · Al 25 A
8 AWG	40	50	55	30	40	45	8.367	—
6 AWG	55	65	75	40	50	55	13.3	—
4 AWG	70	85	95	55	65	75	21.15	—
3 AWG	85	100	115	65	75	85	26.67	—
2 AWG	95	115	130	75	90	100	33.62	—
1 AWG	110	130	145	85	100	115	42.41	—
1/0 AWG	125	150	170	100	120	135	53.49	—
2/0 AWG	145	175	195	115	135	150	67.43	—
3/0 AWG	165	200	225	130	155	175	85.01	—
4/0 AWG	195	230	260	150	180	205	107.2	—
250 kcmil	215	255	290	170	205	230	127	—
300 kcmil	240	285	320	195	230	260	152	—
350 kcmil	260	310	350	210	250	280	177	—
400 kcmil	280	335	380	225	270	305	203	—
500 kcmil	320	380	430	260	310	350	253	—
600 kcmil	350	420	475	285	340	385	304	—
750 kcmil	400	475	535	320	385	435	380	—
1000 kcmil	455	545	615	375	445	500	507	—

NEC 2023 Table 310.16: insulated conductors rated up to and including 2,000 V, 60 °C through 90 °C, not more than three current-carrying conductors in a raceway, cable or earth (directly buried), 30 °C (86 °F) ambient. mm² is the metric area from Chapter 9 Table 8. The 2026 NEC adds values for 16 AWG copper and 14 AWG copper-clad aluminum; this chart follows the 2023 edition that most jurisdictions currently enforce.

This is the starting point, not the answer. Use the column your terminals allow (usually 60 °C for 100 A and below, 75 °C above, per 110.14(C)), NM-B cable at 60 °C (334.80), then apply temperature and bundling corrections. Aluminum needs AL-rated terminals.

Temperature correction, Table 310.15(B)(1)

Multiply the table ampacity by this factor when the ambient temperature isn't 30 °C (86 °F). Rooftops in sunlight, attics and boiler rooms often run far hotter.

Ambient °C (°F)	60 °C	75 °C	90 °C
21–25 (70–77)	1.08	1.05	1.04
26–30 (78–86)	1.00	1.00	1.00
31–35 (87–95)	0.91	0.94	0.96
36–40 (96–104)	0.82	0.88	0.91
41–45 (105–113)	0.71	0.82	0.87
46–50 (114–122)	0.58	0.75	0.82
51–55 (123–131)	0.41	0.67	0.76
56–60 (132–140)	—	0.58	0.71

More than three current-carrying conductors, Table 310.15(C)(1)

Current-carrying conductors	Multiply ampacity by
4–6	80%
7–9	70%
10–20	50%
21–30	45%
31–40	40%
41 and above	35%

Equipment grounding conductors don't count. A neutral that carries only the unbalanced current of other conductors in the same circuit usually doesn't count either (310.15(E)).

Worked example

6 AWG copper THHN in a conduit through a 38 °C space with five current-carrying conductors, landing on 75 °C terminals: 75 A (90 °C column) × 0.91 × 0.80 = 54.6 A. That is below the 65 A 75 °C limit, so 54.6 A is the allowable ampacity.

Questions people ask

How many amps can 12 gauge wire carry?

NEC Table 310.16 lists 12 AWG copper at 20 A (60 °C), 25 A (75 °C) and 30 A (90 °C). NEC 240.4(D) limits its overcurrent protection to 20 A, so it goes on a 20 A breaker.

How many amps can 10 gauge wire carry?

30 A at 60 °C, 35 A at 75 °C and 40 A at 90 °C. 240.4(D) limits the breaker to 30 A.

How many amps can 14 gauge wire carry?

15 A at 60 °C, 20 A at 75 °C, 25 A at 90 °C, and 240.4(D) limits the breaker to 15 A.

Why is aluminum rated lower than copper?

Aluminum has about 61% of copper’s conductivity, so the same size heats more at a given current. Aluminum is typically one to two sizes larger for the same ampacity, and needs terminals rated for aluminum (AL or CU/AL).