WireGauge

Wire Gauge Chart

Every AWG size from 4/0 to 40, with NEC 2026 ampacity for copper and aluminum.

Metal
AWG wire sizes. Resistance: solid conductor at 20 °C. Ampacity: NEC 2026 Table 310.16, 30 °C ambient, up to three current-carrying conductors. Copper shown.
AWG Diameter (in) Diameter (mm) Area (kcmil) Area (mm²) Ω per 1000 ft Ω per km Amps 60 °C Amps 75 °C Amps 90 °C
4/0 0.4600 11.684 211.6 107.2 0.04901 0.1608 195 230 260
3/0 0.4096 10.405 167.8 85.03 0.0618 0.2028 165 200 225
2/0 0.3648 9.266 133.1 67.43 0.07793 0.2557 145 175 195
1/0 0.3249 8.251 105.5 53.48 0.09827 0.3224 125 150 170
1 0.2893 7.348 83.69 42.41 0.1239 0.4066 110 130 145
2 0.2576 6.544 66.37 33.63 0.1563 0.5127 95 115 130
3 0.2294 5.827 52.63 26.67 0.197 0.6464 85 100 115
4 0.2043 5.189 41.74 21.15 0.2485 0.8152 70 85 95
5 0.1819 4.621 33.1 16.77 0.3133 1.028
6 0.1620 4.115 26.25 13.3 0.3951 1.296 55 65 75
7 0.1443 3.665 20.82 10.55 0.4982 1.634
8 0.1285 3.264 16.51 8.366 0.6282 2.061 40 50 55
9 0.1144 2.906 13.09 6.634 0.7921 2.599
10 0.1019 2.588 10.38 5.261 0.9988 3.277 30 35* 40*
11 0.0907 2.305 8.234 4.172 1.26 4.132
12 0.0808 2.053 6.53 3.309 1.588 5.211 20 25* 30*
13 0.0720 1.828 5.178 2.624 2.003 6.571
14 0.0641 1.628 4.107 2.081 2.525 8.285 15 20* 25*
15 0.0571 1.450 3.257 1.65 3.184 10.45
16 0.0508 1.291 2.583 1.309 4.015 13.17
17 0.0453 1.150 2.048 1.038 5.063 16.61
18 0.0403 1.024 1.624 0.823 6.385 20.95
19 0.0359 0.912 1.288 0.6527 8.051 26.41
20 0.0320 0.812 1.022 0.5176 10.15 33.31
21 0.0285 0.723 0.8101 0.4105 12.8 42
22 0.0253 0.644 0.6424 0.3255 16.14 52.96
23 0.0226 0.573 0.5095 0.2582 20.36 66.78
24 0.0201 0.511 0.404 0.2047 25.67 84.21
25 0.0179 0.455 0.3204 0.1624 32.37 106.2
26 0.0159 0.405 0.2541 0.1288 40.81 133.9
27 0.0142 0.361 0.2015 0.1021 51.47 168.9
28 0.0126 0.321 0.1598 0.08098 64.9 212.9
29 0.0113 0.286 0.1267 0.06422 81.83 268.5
30 0.0100 0.255 0.1005 0.05093 103.2 338.5
31 0.0089 0.227 0.0797 0.04039 130.1 426.9
32 0.0080 0.202 0.06321 0.03203 164.1 538.3
33 0.0071 0.180 0.05013 0.0254 206.9 678.8
34 0.0063 0.160 0.03975 0.02014 260.9 856
35 0.0056 0.143 0.03152 0.01597 329 1079
36 0.0050 0.127 0.025 0.01267 414.8 1361
37 0.0045 0.113 0.01983 0.01005 523.1 1716
38 0.0040 0.101 0.01572 0.007967 659.6 2164
39 0.0035 0.090 0.01247 0.006318 831.8 2729
40 0.0031 0.080 0.009888 0.00501 1049 3441

* NEC 240.4(D) limits the breaker for small conductors: copper 14 AWG 15 A, 12 AWG 20 A, 10 AWG 30 A; aluminum 12 AWG 15 A, 10 AWG 25 A. Blank ampacity cells: no 60 or 75 °C rating for building wire in that size (Table 310.16 lists 18 and 16 AWG copper at 90 °C only, for fixture and control wiring).

Use this next

Wire size calculator Wire size from amps, voltage and length, with voltage drop. AWG to mm² converter AWG ↔ mm² with the nearest metric cable size.

American Wire Gauge (AWG) numbers run backwards: the smaller the number, the thicker the wire. Every three gauge numbers the cross-section roughly doubles, and every six the diameter roughly doubles, so 10 AWG has about twice the copper of 13 AWG and twice the diameter of 16 AWG. Sizes thicker than 1 AWG are written 1/0, 2/0, 3/0 and 4/0 ("one aught" to "four aught").

The three ampacity columns are the NEC's allowable currents for insulation rated 60, 75 and 90 °C, with no more than three current-carrying conductors together and a 30 °C (86 °F) surrounding temperature. Most home wiring is NM-B cable ("Romex"), which the NEC limits to the 60 °C column. The 75 °C column applies to wires such as THHN in conduit when the breaker and the equipment terminals are also rated 75 °C. The 90 °C column is mainly a starting point for adjustments, not a size you can pick a breaker from.

For the three smallest common sizes the breaker is capped below the table value. NEC 240.4(D) limits copper 14 AWG to a 15 A breaker, 12 AWG to 20 A and 10 AWG to 30 A, and aluminum 12 AWG to 15 A and 10 AWG to 25 A. Those cells are marked with an asterisk. In practice that gives the familiar home sizes: 14 AWG copper for 15 A circuits, 12 AWG for 20 A circuits and 10 AWG for 30 A circuits such as a dryer or water heater.

The resistance columns are for solid wire at 20 °C (68 °F); stranded wire of the same gauge is a little higher. Resistance is what causes voltage drop on long runs, which is why a circuit can need a bigger wire than the ampacity column alone suggests. For a specific circuit, use the wire size calculator, which checks both.

Use the gauge picker to jump to a size, switch between copper and aluminum, or type a current to see the smallest wire for it. The print button prints the chart on its own, sized to fit one page.

Frequently asked questions

What size wire do I need for 20 amps?

12 AWG copper. NEC 240.4(D) allows a 20 A breaker on 12 AWG copper, and that holds for NM-B cable at 60 °C. On long runs, check voltage drop: a 20 A load 100 feet away at 120 V needs 8 AWG to keep the drop under 3%.

What gauge wire for 30 amps?

10 AWG copper. NEC 240.4(D) caps 10 AWG copper at a 30 A breaker. In aluminum, 8 AWG is needed (35 A at 60 °C).

What gauge wire for 50 amps?

6 AWG copper with NM-B cable (55 A at 60 °C). 8 AWG copper is rated exactly 50 A only where the 75 °C column applies, such as THHN in conduit with 75 °C terminals at both ends.

Is 12 gauge wire thicker than 14 gauge?

Yes. Lower AWG numbers are thicker: 12 AWG is about 2.05 mm across and 14 AWG about 1.63 mm.

What do the 60 °C, 75 °C and 90 °C columns mean?

They are the temperature ratings of the insulation. A wire can carry more current when its insulation tolerates more heat, but the whole circuit is limited by its lowest-rated part, usually the cable type or the breaker and device terminals.