How it works
AWG (American Wire Gauge) is the North American wire size standard: the higher the number, the thinner the wire, and every 3 steps roughly halve the cross-section. 0000 (4/0) is the thickest, 40 a very fine wire.
Formula
d = 0.127 mm × 92^((36 − n) / 39) A = π/4 × d² R = ρ / A (ρCu = 0.01724, ρAl = 0.02826 Ω·mm²/m)
The IEC 60228 metric series does not match AWG, so when substituting always choose the larger cross-section. Resistance applies to solid conductors at 20 °C; stranded wire is slightly higher. Current capacity depends on installation and insulation and must be taken from the relevant standard.
Chart
| AWG | Diameter mm | mm² | Ω/km (copper) |
|---|---|---|---|
| 0000 | 11.684 | 107.219 | 0.16 |
| 000 | 10.405 | 85.029 | 0.20 |
| 00 | 9.266 | 67.431 | 0.26 |
| 0 | 8.252 | 53.475 | 0.32 |
| 1 | 7.348 | 42.408 | 0.41 |
| 2 | 6.544 | 33.631 | 0.51 |
| 3 | 5.827 | 26.671 | 0.65 |
| 4 | 5.189 | 21.151 | 0.82 |
| 5 | 4.621 | 16.773 | 1.03 |
| 6 | 4.115 | 13.302 | 1.30 |
| 7 | 3.665 | 10.549 | 1.63 |
| 8 | 3.264 | 8.366 | 2.06 |
| 9 | 2.906 | 6.634 | 2.60 |
| 10 | 2.588 | 5.261 | 3.28 |
| 11 | 2.305 | 4.172 | 4.13 |
| 12 | 2.053 | 3.309 | 5.21 |
| 13 | 1.828 | 2.624 | 6.57 |
| 14 | 1.628 | 2.081 | 8.29 |
| 15 | 1.450 | 1.650 | 10.45 |
| 16 | 1.291 | 1.309 | 13.17 |
| 17 | 1.149 | 1.038 | 16.61 |
| 18 | 1.024 | 0.823 | 20.95 |
| 19 | 0.912 | 0.653 | 26.41 |
| 20 | 0.812 | 0.518 | 33.31 |
| 21 | 0.723 | 0.410 | 42.00 |
| 22 | 0.644 | 0.326 | 52.97 |
| 23 | 0.573 | 0.258 | 66.77 |
| 24 | 0.511 | 0.205 | 84.23 |
| 25 | 0.455 | 0.162 | 106.16 |
| 26 | 0.405 | 0.129 | 133.86 |
| 27 | 0.361 | 0.102 | 168.86 |
| 28 | 0.321 | 0.081 | 212.85 |
| 29 | 0.286 | 0.064 | 268.55 |
| 30 | 0.255 | 0.051 | 338.72 |
| 31 | 0.227 | 0.040 | 426.76 |
| 32 | 0.202 | 0.032 | 538.78 |
| 33 | 0.180 | 0.025 | 678.78 |
| 34 | 0.160 | 0.020 | 857.76 |
| 35 | 0.143 | 0.016 | 1,077.56 |
| 36 | 0.127 | 0.013 | 1,357.56 |
| 37 | 0.113 | 0.010 | 1,724.10 |
| 38 | 0.101 | 0.008 | 2,155.12 |
| 39 | 0.090 | 0.006 | 2,736.67 |
| 40 | 0.080 | 0.005 | 3,448.20 |
All calculations run in your browser; your inputs never reach us.