Convert between AWG and mm² wire sizes, with diameter and indicative ampacity for copper conductors.
AWG (American Wire Gauge) is a wire sizing system where smaller numbers mean thicker wires. It is defined by ASTM B258, and the rule is geometric: each step changes the diameter by a factor of about 1.123, which means the cross-sectional area roughly doubles every six gauges. AWG 10 has a cross-section of about 5.26 mm², AWG 4 has about 21.15 mm², and the thickest standard gauge, 4/0 (0000), has about 107 mm².
Brazil uses metric cross-sections (mm²) as defined by NBR 5410, so the conversion between AWG and mm² is the most common lookup. The table on this page gives the exact ASTM B258 diameter, the computed cross-section (π/4 × d²), and an indicative ampacity for copper wire with 60°C insulation — the simplest case from NEC Table 310.16. The ampacity is indicative because it depends on the insulation type, the number of conductors, the ambient temperature and the installation method.
This page is a reference, not a sizing tool. Choosing the right wire gauge for an installation requires applying the derating factors from NBR 5410 or the NEC, and that is the job of a licensed electrician. The ampacity figures here are a starting point for comparison, not a specification. Everything runs in your browser.
AWG to diameter: d(mm) = 0.127 × 92^((36 − AWG)/39). Cross-section: A(mm²) = π/4 × d². The table values are from ASTM B258, not computed from this formula, but they agree to the third decimal.
Because AWG originally counted the number of drawing dies the wire was pulled through. More draws made thinner wire, so a higher number meant a thinner result. The convention stuck.
AWG 14 ≈ 2.08 mm² (close to 2.5 mm²), AWG 12 ≈ 3.31 mm² (close to 4 mm²), AWG 10 ≈ 5.26 mm² (close to 6 mm²). The metric and AWG sizes do not align exactly.
No. Wire sizing depends on the load, the insulation, the installation method, the ambient temperature and the number of conductors. Use NBR 5410 or NEC 310.16 with the correct derating factors, and have a licensed electrician do the work.
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