The formula
For gauges thicker than 1 AWG, use 0 for 1/0, −1 for 2/0, −2 for 3/0 and −3 for 4/0 in the formula.
Wire gauge chart
| Gauge | Diameter (mm) | Diameter (in) | Area (mm²) | Ω per km (copper, 20 °C) | Ω per 1,000 ft |
|---|---|---|---|---|---|
| 4/0 AWG | 11.68 | 0.460 | 107.22 | 0.161 | 0.0490 |
| 3/0 AWG | 10.40 | 0.410 | 85.03 | 0.203 | 0.0618 |
| 2/0 AWG | 9.27 | 0.365 | 67.43 | 0.256 | 0.0779 |
| 1/0 AWG | 8.25 | 0.325 | 53.48 | 0.322 | 0.0983 |
| 1 AWG | 7.35 | 0.289 | 42.41 | 0.407 | 0.1239 |
| 2 AWG | 6.54 | 0.258 | 33.63 | 0.513 | 0.1562 |
| 3 AWG | 5.83 | 0.229 | 26.67 | 0.646 | 0.1970 |
| 4 AWG | 5.19 | 0.204 | 21.15 | 0.815 | 0.2484 |
| 6 AWG | 4.12 | 0.162 | 13.30 | 1.296 | 0.3950 |
| 8 AWG | 3.26 | 0.128 | 8.37 | 2.061 | 0.6281 |
| 10 AWG | 2.59 | 0.102 | 5.26 | 3.277 | 0.9988 |
| 12 AWG | 2.05 | 0.081 | 3.31 | 5.210 | 1.5881 |
| 14 AWG | 1.63 | 0.064 | 2.08 | 8.285 | 2.5252 |
| 16 AWG | 1.29 | 0.051 | 1.31 | 13.173 | 4.0153 |
| 18 AWG | 1.02 | 0.040 | 0.82 | 20.947 | 6.3845 |
| 20 AWG | 0.81 | 0.032 | 0.52 | 33.306 | 10.1518 |
| 22 AWG | 0.64 | 0.025 | 0.33 | 52.959 | 16.1419 |
| 24 AWG | 0.51 | 0.020 | 0.20 | 84.208 | 25.6667 |
AWG vs metric cable
AWG sizes don't line up exactly with metric sizes. When converting, round up to the next metric size: 10 AWG (5.26 mm²) becomes 6 mm², 4 AWG (21.2 mm²) becomes 25 mm². Note that some cheap cable is labelled with a gauge number but has less copper than the standard, so check the actual mm² or strand count if you can.
Current ratings are guide figures for single-core copper cable. 'Standard PVC' uses conservative values for 70 °C insulation, bundled or enclosed; '105 °C' uses typical marine-table values for high-temperature cable run on its own. Always check the cable maker's rating, and derate for hot spaces such as engine bays.
Frequently asked questions
What is 10 AWG in mm²?
10 AWG is 5.26 mm². The nearest metric cable that's at least as thick is 6 mm².
What is 4 AWG in mm²?
4 AWG is 21.2 mm², so use 25 mm² metric cable as an equivalent.
Is 6mm² cable the same as 10 AWG?
Close. 6 mm² is slightly thicker than 10 AWG (5.26 mm²), so it can replace it.