AWG wire size chart
Diameter, cross-section and resistance for any AWG size from 4/0 to 40, with the full chart and your gauge highlighted.
Diameter, 12 AWG
2.053mm
- Cross-section
- 3.309 mm²
- Cross-section, circular mils
- 6.53 kcmil
- Resistance, solid copper, 20 °C
- 5.211 Ω/km
AWG sizes, solid copper at 20 °C
| AWG | Diameter (mm) | Diameter (in) | Area (mm²) | Area (kcmil) | Ω/km | Ω/1000 ft |
|---|---|---|---|---|---|---|
| 4/0 (0000) | 11.68 | 0.46 | 107.2 | 211.6 | 0.1608 | 0.04901 |
| 3/0 (000) | 10.4 | 0.4096 | 85.03 | 167.8 | 0.2028 | 0.0618 |
| 2/0 (00) | 9.266 | 0.3648 | 67.43 | 133.1 | 0.2557 | 0.07793 |
| 1/0 (0) | 8.251 | 0.3249 | 53.48 | 105.5 | 0.3224 | 0.09827 |
| 1 | 7.348 | 0.2893 | 42.41 | 83.69 | 0.4066 | 0.1239 |
| 2 | 6.544 | 0.2576 | 33.63 | 66.37 | 0.5127 | 0.1563 |
| 3 | 5.827 | 0.2294 | 26.67 | 52.63 | 0.6465 | 0.197 |
| 4 | 5.189 | 0.2043 | 21.15 | 41.74 | 0.8152 | 0.2485 |
| 5 | 4.621 | 0.1819 | 16.77 | 33.1 | 1.028 | 0.3133 |
| 6 | 4.115 | 0.162 | 13.3 | 26.25 | 1.296 | 0.3951 |
| 7 | 3.665 | 0.1443 | 10.55 | 20.82 | 1.634 | 0.4982 |
| 8 | 3.264 | 0.1285 | 8.366 | 16.51 | 2.061 | 0.6282 |
| 9 | 2.906 | 0.1144 | 6.634 | 13.09 | 2.599 | 0.7921 |
| 10 | 2.588 | 0.1019 | 5.261 | 10.38 | 3.277 | 0.9989 |
| 11 | 2.305 | 0.09074 | 4.172 | 8.234 | 4.132 | 1.26 |
| 12 | 2.053 | 0.08081 | 3.309 | 6.53 | 5.211 | 1.588 |
| 13 | 1.828 | 0.07196 | 2.624 | 5.178 | 6.571 | 2.003 |
| 14 | 1.628 | 0.06408 | 2.081 | 4.107 | 8.286 | 2.525 |
| 15 | 1.45 | 0.05707 | 1.65 | 3.257 | 10.45 | 3.184 |
| 16 | 1.291 | 0.05082 | 1.309 | 2.583 | 13.17 | 4.016 |
| 17 | 1.15 | 0.04526 | 1.038 | 2.048 | 16.61 | 5.064 |
| 18 | 1.024 | 0.0403 | 0.823 | 1.624 | 20.95 | 6.385 |
| 19 | 0.9116 | 0.03589 | 0.6527 | 1.288 | 26.42 | 8.051 |
| 20 | 0.8118 | 0.03196 | 0.5176 | 1.022 | 33.31 | 10.15 |
| 21 | 0.7229 | 0.02846 | 0.4105 | 0.8101 | 42 | 12.8 |
| 22 | 0.6438 | 0.02535 | 0.3255 | 0.6424 | 52.96 | 16.14 |
| 23 | 0.5733 | 0.02257 | 0.2582 | 0.5095 | 66.79 | 20.36 |
| 24 | 0.5106 | 0.0201 | 0.2047 | 0.404 | 84.22 | 25.67 |
| 25 | 0.4547 | 0.0179 | 0.1624 | 0.3204 | 106.2 | 32.37 |
| 26 | 0.4049 | 0.01594 | 0.1288 | 0.2541 | 133.9 | 40.81 |
| 27 | 0.3606 | 0.0142 | 0.1021 | 0.2015 | 168.9 | 51.47 |
| 28 | 0.3211 | 0.01264 | 0.08098 | 0.1598 | 212.9 | 64.9 |
| 29 | 0.2859 | 0.01126 | 0.06422 | 0.1267 | 268.5 | 81.84 |
| 30 | 0.2546 | 0.01003 | 0.05093 | 0.1005 | 338.6 | 103.2 |
| 31 | 0.2268 | 0.008928 | 0.04039 | 0.0797 | 426.9 | 130.1 |
| 32 | 0.2019 | 0.00795 | 0.03203 | 0.06321 | 538.3 | 164.1 |
| 33 | 0.1798 | 0.00708 | 0.0254 | 0.05013 | 678.8 | 206.9 |
| 34 | 0.1601 | 0.006305 | 0.02014 | 0.03975 | 856 | 260.9 |
| 35 | 0.1426 | 0.005615 | 0.01597 | 0.03152 | 1079 | 329 |
| 36 | 0.127 | 0.005 | 0.01267 | 0.025 | 1361 | 414.8 |
| 37 | 0.1131 | 0.004453 | 0.01005 | 0.01983 | 1716 | 523.1 |
| 38 | 0.1007 | 0.003965 | 0.007967 | 0.01572 | 2164 | 659.6 |
| 39 | 0.08969 | 0.003531 | 0.006318 | 0.01247 | 2729 | 831.8 |
| 40 | 0.07987 | 0.003145 | 0.00501 | 0.009888 | 3441 | 1049 |
Method
How this is calculated
d = 0.127 mm × 92^((36 − n) / 39) n = 0 for 1/0, −1 for 2/0, −3 for 4/0 A = d² in circular mils; 1 cmil = 5.067 × 10⁻⁴ mm² R20 = ρ20 / A, ρ20 = 1/58 Ω·mm²/m (100 % IACS copper) Aluminium: 61 % IACS, R = R_copper / 0.61
- Geometry
- ASTM B258 defines 36 AWG as 0.005 in and 4/0 as 0.46 in, with 39 equal geometric steps between them; Bureau of Standards Circular 31 sets out the same definition. The chart shows the formula value to 4 significant figures.
- Resistance
- Solid wire at 20 °C. Stranded wire of the same gauge has slightly higher resistance: NEC Chapter 9 Table 8 lists 12 AWG copper at 1.93 Ω/1000 ft solid and 1.98 stranded, both at 75 °C.
- Aluminum
- 61 % IACS conductivity, the value used for NEC Chapter 9 Table 8.
Sources
- ASTM B258, Standard Specification for Standard Nominal Diameters and Cross-Sectional Areas of AWG Sizes of Solid Round Wires Used as Electrical ConductorsB258-18, reapproved 2026
- International Annealed Copper Standard: 1.7241 µΩ·cm (58 MS/m) at 20 °C, 0.00393 per °C; AWG 0000 = 0.4600 in, 36 = 0.0050 in; Table VII resistancesUS Bureau of Standards Circular 31, Copper Wire Tables, 3rd edition, 1914
- NFPA 70, National Electrical Code, as published by Public.Resource.Org: Chapter 9 Table 8, note 4 (61 % IACS aluminum) and solid conductor cross-check2017 edition
FAQ
Questions
2.053 mm (0.0808 in) for the bare conductor, with an area of 3.309 mm² (6.53 kcmil). Insulated 12 AWG THHN is about 0.130 in (3.30 mm) over the insulation per NEC Chapter 9 Table 5.
Each step changes the diameter by the 39th root of 92, about 1.123, and the area by about 1.261. Three gauges double or halve the area: 10 AWG is 5.26 mm² and 13 AWG is 2.62 mm².
Solid copper at 20 °C is 52.96 Ω/km (16.14 Ω per 1000 ft). A 1 m pair (2 m of conductor) at 100 mA drops about 10.6 mV.
Area in mm² is π/4 × d², with d = 0.127 mm × 92^((36 − n)/39). Common equivalents: 18 AWG 0.823 mm², 14 AWG 2.08 mm², 10 AWG 5.26 mm², 4/0 107.2 mm².
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