Copper wire resistance table (AWG and mm²)
Resistance of a single copper conductor at 20 °C. For a loop, count both conductors.
AWG sizes
| Size | Diameter (mm) | Cross-section (mm²) | Ω/km | Ω/1000 ft |
|---|---|---|---|---|
| AWG 10 | 2.588 | 5.261 | 3.269 | 0.9965 |
| AWG 12 | 2.053 | 3.309 | 5.198 | 1.584 |
| AWG 14 | 1.628 | 2.081 | 8.266 | 2.519 |
| AWG 16 | 1.291 | 1.309 | 13.14 | 4.006 |
| AWG 18 | 1.024 | 0.823 | 20.9 | 6.37 |
| AWG 20 | 0.812 | 0.5176 | 33.23 | 10.13 |
| AWG 22 | 0.644 | 0.3255 | 52.84 | 16.1 |
| AWG 24 | 0.511 | 0.2047 | 84.01 | 25.61 |
| AWG 26 | 0.405 | 0.1288 | 133.6 | 40.72 |
| AWG 28 | 0.321 | 0.08098 | 212.4 | 64.74 |
| AWG 30 | 0.255 | 0.05093 | 337.7 | 102.9 |
Metric sizes
| Size | Diameter (mm) | Cross-section (mm²) | Ω/km | Ω/1000 ft |
|---|---|---|---|---|
| 0.14 mm² | 0.422 | 0.14 | 122.9 | 37.45 |
| 0.25 mm² | 0.564 | 0.25 | 68.8 | 20.97 |
| 0.34 mm² | 0.658 | 0.34 | 50.59 | 15.42 |
| 0.5 mm² | 0.798 | 0.5 | 34.4 | 10.49 |
| 0.75 mm² | 0.977 | 0.75 | 22.93 | 6.99 |
| 1 mm² | 1.128 | 1 | 17.2 | 5.243 |
| 1.5 mm² | 1.382 | 1.5 | 11.47 | 3.495 |
| 2.5 mm² | 1.784 | 2.5 | 6.88 | 2.097 |
| 4 mm² | 2.257 | 4 | 4.3 | 1.311 |
| 6 mm² | 2.764 | 6 | 2.867 | 0.8738 |
Calculated with ρ = 0.0172 Ω·mm²/m (copper at 20 °C), the value used by the loop power and RTD wiring calculators. AWG diameters follow d = 0.127 mm × 92^((36 − n)/39) for solid wire. Resistance rises about 0.39 % per °C; stranded and tinned conductors are slightly higher.