Wire

Wire Gauge Calculator — ChiefEngineer.in

Convert AWG or SWG gauge to diameter, cross-section and DC resistance.

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Formula

AWG: d = 0.127 × 92(36−n)/39

A = πd²/4

R = ρ·L/A (ρCu=0.0175, ρAl=0.028 Ω·mm²/m)

Variables

  • n — AWG gauge number
  • d — diameter (mm)
  • A — area (mm²)
  • R — resistance per km at 20 °C

Worked Example

Input: AWG 12, copper

Result: d ≈ 2.0525 mm, A ≈ 3.309 mm², R ≈ 5.29 Ω/km

Assumptions & Notes

AWG formula assumes solid round conductor. Stranded conductors use nominal sizes that may differ. Resistance is DC at 20 °C; AC has skin effect and temperature correction.

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