Wire Gauge (AWG) Calculator

Understanding AWG Wire Gauges

The American Wire Gauge (AWG) system rates wire by diameter, but counterintuitively — a higher AWG number means a thinner wire. AWG 4/0 (0000) is the thickest commonly used; AWG 40 is hair-thin. Each 3-step increase in AWG number halves the cross-sectional area and roughly halves the current capacity.

AWG to mm² Conversion

Diameter (mm) = 0.127 × 92^((36 − AWG) / 39) Area (mm²) = π × (Diameter / 2)²

Current Capacity (Ampacity) Reference

| AWG | mm² | Max Current (in conduit) | |-----|-----|--------------------------| | 14 | 2.08 | 15A | | 12 | 3.31 | 20A | | 10 | 5.26 | 30A | | 8 | 8.37 | 50A | | 6 | 13.3 | 65A | | 4 | 21.1 | 85A | | 2 | 33.6 | 115A |

How to Use This Calculator

Enter AWG gauge to get mm², diameter, resistance per metre, and maximum ampacity. Or enter current and cable length to find the minimum AWG gauge.

Practical Examples

Example 1: 20A circuit in a US home: use AWG 12 minimum (20A rating).

Example 2: 100A service entrance: use AWG 4/0 copper or AWG 250kcmil aluminium.

AWG vs Metric (mm²)

Metric cable sizes (1.5mm², 2.5mm², 4mm², 6mm², 10mm²) are used in Europe, Asia, and most of the world. This calculator converts between both systems for international projects.