Convert AWG to diameter (mm & inch), cross-section area (mm²), resistance per metre and maximum current — or reverse-lookup the AWG from mm² or diameter.
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AWG Reference Table
Copper wire at 20 °C. Ampacity based on NEC Table 310.16 (60 °C insulation, in conduit) and free-air ratings.
AWG
Diameter (mm)
Diameter (in)
Area (mm²)
Resistance (Ω/m)
Ampacity (conduit)
Ampacity (free air)
Frequently Asked Questions
What is AWG (American Wire Gauge)? ▾
AWG is a standardised wire gauge system used mainly in North America. A lower AWG number means a thicker wire with higher current capacity. AWG 0000 (4/0) is the thickest common gauge, while AWG 40 is extremely thin hair-like wire used in precision coils.
How do I convert AWG to mm²? ▾
The formula is: diameter (mm) = 0.127 × 92^((36 − AWG) / 39), then area (mm²) = π / 4 × diameter². For example, AWG 12 has a diameter of 2.053 mm and an area of 3.31 mm².
What AWG is 2.5 mm² wire (common in EU)? ▾
2.5 mm² (standard European socket circuit wire) is closest to AWG 13 (2.63 mm²). The nearest standard US size is AWG 12 (3.31 mm²), which is the usual substitute and is rated for 20 A circuits.
Does higher AWG mean thicker or thinner wire? ▾
Higher AWG = thinner wire. AWG 30 is much thinner than AWG 10. The number reflects how many times the wire was drawn through a progressively smaller die — more draws produces a thinner wire.
What is the maximum current for AWG 12 wire? ▾
AWG 12 copper wire is rated for 20 A in conduit (NEC, 60 °C insulation) and up to 41 A in free air. It is the standard wire for 20 A household branch circuits in North America.