AWG to mm²: Complete Wire Gauge Conversion Guide
AWG vs Metric Wire Gauge
The American Wire Gauge (AWG) system is used in North America. The metric system (mm²) is used in Europe, Asia, and most of the world. They measure the same thing — wire cross-sectional area — but use different scales.
Key differences:
- AWG numbers decrease as wire size increases (14 AWG is thinner than 10 AWG)
- mm² increases with wire size (2.5 mm² is thinner than 6 mm²)
- Going down 3 AWG numbers ≈ doubles the area
- Going up 3 AWG numbers ≈ halves the area
Complete AWG to mm² Conversion Chart
| AWG | Diameter (mm) | Area (mm²) | Area (cmils) | Metric Equivalent | Cu Ampacity* |
|---|---|---|---|---|---|
| 4/0 | 11.68 | 107.2 | 211,600 | 120 mm² | 230A |
| 3/0 | 10.40 | 85.0 | 167,800 | 95 mm² | 200A |
| 2/0 | 9.27 | 67.4 | 133,100 | 70 mm² | 175A |
| 1/0 | 8.25 | 53.5 | 105,600 | 50 mm² | 150A |
| 1 | 7.35 | 42.4 | 83,690 | 50 mm² | 130A |
| 2 | 6.54 | 33.6 | 66,370 | 35 mm² | 115A |
| 4 | 5.19 | 21.2 | 41,740 | 25 mm² | 85A |
| 6 | 4.11 | 13.3 | 26,250 | 16 mm² | 65A |
| 8 | 3.26 | 8.37 | 16,510 | 10 mm² | 50A |
| 10 | 2.59 | 5.26 | 10,380 | 6 mm² | 35A |
| 12 | 2.05 | 3.31 | 6,530 | 4 mm² | 25A |
| 14 | 1.63 | 2.08 | 4,110 | 2.5 mm² | 20A |
| 16 | 1.29 | 1.31 | 2,580 | 1.5 mm² | — |
| 18 | 1.02 | 0.823 | 1,620 | 1.0 mm² | — |
*Ampacity at 75°C insulation (THWN). NEC 240.4(D) limits 14 AWG to 15A and 12 AWG to 20A for overcurrent protection.
Common International Wire Sizes
| IEC mm² | Nearest AWG | Ampacity (Cu, 70°C) | Common Use |
|---|---|---|---|
| 0.5 | 20 AWG | 3A | Signal, low-voltage |
| 0.75 | 18 AWG | 6A | Lighting, appliances |
| 1.0 | 17 AWG | 10A | Lighting circuits |
| 1.5 | 16 AWG | 13A | 10A lighting, 13A sockets (UK) |
| 2.5 | 14 AWG | 18A | 16A power circuits (EU) |
| 4.0 | 12 AWG | 24A | 20A power circuits |
| 6.0 | 10 AWG | 31A | 32A circuits, cookers |
| 10 | 8 AWG | 42A | Submains, motors |
| 16 | 6 AWG | 56A | Feeders, large motors |
| 25 | 4 AWG | 73A | Service entrance |
How to Convert AWG to mm²
Formula: A(mm²) = 0.01267 × 92^((36−AWG)/19.5)
Simplified for common gauges: each 3 AWG decrease ≈ 2× area.
14 AWG → 11 AWG ≈ 2× → 8 AWG ≈ 4× → 5 AWG ≈ 8× of 14 AWG area.
Common Mistakes
- Using the nearest AWG instead of exact metric: 2.5 mm² ≈ 14 AWG, but they're not identical. When working with IEC equipment, use the specified metric size.
- Confusing diameter with area: mm diameter ≠ mm² area. A 2.0 mm diameter wire has π × 1.0² = 3.14 mm² area.
- Ignoring insulation thickness: AWG/mm² measures the conductor only. Overall cable diameter includes insulation.
Standards Reference
- NEC Chapter 9, Table 8 — Conductor Properties
- IEC 60228 — Conductors of Insulated Cables
- ASTM B258 — Standard Conductor Sizes
- BS 6004 — UK Metric Wire Standard
Frequently Asked Questions
What is 12 AWG in mm²?
12 AWG = 3.31 mm² (nearest IEC size: 4 mm²). The actual cross-sectional area is 3.31 mm², which corresponds to a diameter of 2.05 mm. In IEC metric systems, 4 mm² wire is the standard equivalent.
What is 2.5 mm² in AWG?
2.5 mm² ≈ 14 AWG (actual: 2.08 mm²). The metric 2.5 mm² wire is slightly thinner than 14 AWG but is the standard IEC size used in European and Asian installations for 16A circuits.
Why does AWG decrease as wire gets bigger?
AWG is based on the number of drawing dies the wire passes through during manufacturing. More dies = thinner wire = higher gauge number. It's a historical manufacturing convention, not a measurement of size directly.
Can I mix AWG and metric wire?
Avoid mixing if possible. AWG and metric wires have slightly different diameters, which affects terminal connections. If you must splice them, use proper connectors rated for both sizes and verify the connection is tight.
What gauge wire do European countries use?
Europe uses IEC metric sizes: 1.5 mm² for lighting (10A), 2.5 mm² for power sockets (16A), 4 mm² for high-power circuits (20A), and 6 mm² for cookers and showers (32A). These are standardized across the EU under HD 60364.