4 AWG to mm² – Wire Size & Diameter
4 AWG = 21.151 mm²
4 AWG solid wire has a cross-section of 21.151 mm² and a diameter of 5.189 mm (0.2043 in).
Step by step
- Diameter: d = 0.127 × 92^((36 − 4)/39) = 5.1894 mm.
- Area: π/4 × d² = 21.1506 mm².
4 AWG is a mid-size gauge for appliance and feeder circuits.
Details
- Area
- 21.151 mm²
- Diameter
- 5.189 mm (0.2043 in)
- Area in kcmil
- 41.74
- Nearest metric size
- 25 mm²
- Copper resistance
- 0.815 Ω/km
How it works
The American Wire Gauge system is logarithmic: smaller numbers mean thicker wire, every 6 gauges halve the diameter and every 3 gauges roughly halve the area. Metric wire is specified directly by cross-sectional area in mm², so the sizes never line up exactly. When substituting, choose a conductor with at least the same area, and always follow local electrical codes.
Nearby values
Related conversions
Frequently asked questions
What is 4 AWG in mm²?
21.151 mm².
What is the diameter of 4 AWG wire?
5.189 mm (solid conductor).
What metric wire replaces 4 AWG?
Use the next metric size up with at least 21.15 mm².
Is stranded wire the same size?
Stranded wire of the same gauge has the same copper area but a slightly larger overall diameter.