12 AWG wire size
2.053 mm · 3.309 mm²
0.0808 in diameter · 5.21 Ω/km in copper · 20 A (NEC 60 °C copper)
What 12 AWG is used for
20-amp circuits — kitchen and bathroom outlets, most of a modern house.
The numbers
| Diameter | 2.053 mm · 0.0808 in |
| Cross-sectional area | 3.3088 mm² |
| Resistance, copper | 5.21 Ω/km · 1.588 Ω per 1,000 ft |
| Resistance, aluminium | 8.523 Ω/km |
| NEC 60 °C copper ampacity | 20 A |
How 12 compares
The gauge scale is geometric, so the useful comparisons are ratios rather than differences. 6 AWG is twice the diameter, which is four times the area.
| Gauge | Diameter | Area | Ω/km copper | vs 12 |
|---|---|---|---|---|
| 6 | 4.115 mm | 13.302 mm² | 1.3 | 4.02× the area |
| 8 | 3.264 mm | 8.366 mm² | 2.06 | 2.53× the area |
| 10 | 2.588 mm | 5.261 mm² | 3.28 | 1.59× the area |
| 14 | 1.628 mm | 2.081 mm² | 8.28 | 0.63× the area |
| 16 | 1.291 mm | 1.309 mm² | 13.17 | 0.4× the area |
| 18 | 1.024 mm | 0.823 mm² | 20.95 | 0.25× the area |
Frequently asked questions
What is 12 AWG in mm?
2.053 mm in diameter (0.0808 inches), with a cross-sectional area of 3.309 mm².
How many amps can 12 AWG copper carry?
20 A under the NEC 60 °C copper column, which is the figure that sets the breaker on an ordinary branch circuit. This is a starting point and not a permission: the real limit depends on insulation rating, ambient temperature, how many conductors share the run, and your local code.
What is the resistance of 12 AWG copper?
5.21 Ω per kilometre, or 1.588 Ω per 1,000 feet, for annealed copper at 20 °C. The same gauge in aluminium is about 8.52 Ω/km — 1.64 times higher, which is why aluminium wiring is sized larger for the same load.
Why do smaller AWG numbers mean thicker wire?
The number counts drawing operations. Wire is pulled through progressively smaller dies, and the gauge records how many passes it took — so more passes means a higher number and a thinner wire.