NEC Table 310.16 conductor ampacity for copper and aluminum at 60/75/90 °C, with ambient temperature and conductor bundling corrections.
Temperature correction: 60 °C ×1.00, 75 °C ×1.00, 90 °C ×1.00.
Bundling adjustment (3 conductors): ×1.00.
Size
mm²
60 °C
75 °C
90 °C
60 °C corrected
75 °C corrected
90 °C corrected
14 AWG
2.08
15
20
25
15
20
25
12 AWG
3.31
20
25
30
20
25
30
10 AWG
5.26
30
35
40
30
35
40
8 AWG
8.37
40
50
55
40
50
55
6 AWG
13.3
55
65
75
55
65
75
4 AWG
21.15
70
85
95
70
85
95
3 AWG
26.67
85
100
115
85
100
115
2 AWG
33.63
95
115
130
95
115
130
1 AWG
42.41
110
130
145
110
130
145
1/0 AWG
53.48
125
150
170
125
150
170
2/0 AWG
67.43
145
175
195
145
175
195
3/0 AWG
85.03
165
200
225
165
200
225
4/0 AWG
107.22
195
230
260
195
230
260
250 kcmil
126.68
215
255
290
215
255
290
300 kcmil
152.01
240
285
320
240
285
320
350 kcmil
177.35
260
310
350
260
310
350
400 kcmil
202.68
280
335
380
280
335
380
500 kcmil
253.35
320
380
430
320
380
430
600 kcmil
304.02
350
420
475
350
420
475
750 kcmil
380.03
400
475
535
400
475
535
1000 kcmil
506.71
455
545
615
455
545
615
Based on NEC Table 310.16: not more than three current-carrying conductors in a raceway, cable or earth, 30 °C ambient.
Small conductors are also limited by NEC 240.4(D) overcurrent protection (Cu: 14 AWG 15 A, 12 AWG 20 A, 10 AWG 30 A; Al: 12 AWG 15 A, 10 AWG 25 A),
and terminations are usually rated 60 °C (≤ 100 A) or 75 °C. Always verify against the code edition adopted locally.
About this wire ampacity table and calculator
Look up the allowable ampacity of copper and aluminum conductors from NEC Table 310.16 at 60, 75 and 90 °C, and apply the ambient temperature correction and the adjustment for more than three current-carrying conductors. Enter a load current to find the smallest suitable wire size.
How to use the Ampacity Table & Calculator
Choose copper or aluminum.
Enter the ambient temperature and number of current-carrying conductors.
Enter the load to highlight the smallest conductor.
Example
12 AWG Cu, 75 °C, 40 °C ambient → 25 A × 0.88 = 22 A
Frequently asked questions
Why can 12 AWG only be protected at 20 A?
NEC 240.4(D) limits overcurrent protection for small conductors regardless of the table ampacity: 14 AWG Cu 15 A, 12 AWG Cu 20 A, 10 AWG Cu 30 A.
Which temperature column should I use?
Usually the lowest temperature rating of the conductor, terminals and connected devices; 60 °C for circuits up to 100 A unless equipment is marked 75 °C.
Is my data safe?
Yes. The tool runs entirely in your browser using WebAssembly. Nothing you type or upload is sent to a server, logged or stored.
Is it free?
Yes, completely free with no sign-up, no limits and no watermarks. It also works offline once the page has loaded.
