12 AWG
2.05 mm across and 3.31 mm², with about 5.21 Ω per km in copper.
Wire Gauge Converter (AWG to mm²)
Convert AWG wire sizes to diameter and mm², with resistance per kilometre and a metric size table.
From 40 up to 4/0 (also written 0000).
Result
12 AWG
3.309mm²
- Diameter
- 2.053 mm (0.0808 in)
- Copper resistance at 20 °C
- 5.211 Ω/km
- Aluminium resistance at 20 °C
- 8.523 Ω/km
Metric sizes and the nearest AWG at least as thick
| Metric size | AWG |
|---|---|
| 0.5 mm² | 20 (0.52 mm²) |
| 0.75 mm² | 18 (0.82 mm²) |
| 1 mm² | 17 (1.04 mm²) |
| 1.5 mm² | 15 (1.65 mm²) |
| 2.5 mm² | 13 (2.62 mm²) |
| 4 mm² | 11 (4.17 mm²) |
| 6 mm² | 9 (6.63 mm²) |
| 10 mm² | 7 (10.55 mm²) |
| 16 mm² | 5 (16.77 mm²) |
| 25 mm² | 3 (26.67 mm²) |
| 35 mm² | 1 (42.41 mm²) |
| 50 mm² | 0 (53.48 mm²) |
| 70 mm² | 3/0 (85.03 mm²) |
| 95 mm² | 4/0 (107.22 mm²) |
| 120 mm² | larger than 4/0 |
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How the Wire Gauge Converter (AWG to mm²) works
American Wire Gauge (AWG) numbers get smaller as wires get thicker. Enter a gauge from 40 up to 4/0 to see its diameter, cross-section in mm² and resistance per kilometre for copper and aluminium at 20 °C. The table maps common metric sizes to the nearest AWG that is at least as thick.
Formulas
Diameter
d = 0.127 mm × 92(36 − n) ÷ 39
For 0, 00, 000 and 0000 (1/0–4/0), n is 0, −1, −2 and −3.
Resistance
Ω per km = ρ ÷ area × 1,000, ρ(copper) = 0.017241 Ω·mm²/m
Examples
Matching a 2.5 mm² cable
The nearest AWG at least as thick is 13 AWG (2.62 mm²).
Frequently asked questions
Why do smaller numbers mean thicker wire?
The gauge counted how many times wire was drawn through dies — more draws made it thinner.
Can I choose a wire size from this?
It gives sizes and resistance; the current a wire may carry depends on insulation, installation and local codes.
What about stranded wire?
Stranded wire of the same gauge has about the same copper area but a slightly larger outer diameter.
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