AWG to mm² Wire Gauge Converter

How to use the AWG to mm² Wire Gauge Converter

1. Choose a direction: AWG → mm², mm² → AWG or Diameter → AWG.
2. Select a gauge or type a size. Results update instantly.
3. Use the chart below to compare all gauges at a glance.

Example

A US product manual asks for 12 AWG wire, but European shops sell cable in mm². 12 AWG is 3.31 mm², so 4 mm² is the next standard metric size up. Going the other way, common 2.5 mm² house wiring sits between 14 AWG (2.08 mm²) and 12 AWG (3.31 mm²), closest to 13 AWG.

When converting, always round to the thicker wire to make sure it can carry the current.

How it works

AWG is a logarithmic scale: smaller numbers mean thicker wire. Every 6 gauges halve the diameter, and every 3 gauges roughly halve the cross-sectional area. The diameter of AWG gauge n is:

d = 0.127 mm × 92(36 − n) ÷ 39

Gauges thicker than 1 AWG are written 1/0, 2/0, 3/0 and 4/0 (“one-aught” to “four-aught”), which correspond to n = 0, −1, −2 and −3. The area is π ÷ 4 × d², and the resistance per kilometer of copper is 0.017241 ÷ area × 1000.

kcmil (thousand circular mils) is used in North America for large cables; 1 kcmil ≈ 0.5067 mm².

AWG to mm² chart

Solid copper at 20 °C. Stranded wire of the same gauge has a slightly larger overall diameter.

Converting between US and metric wire safely

• Always round up: when a manual says 12 AWG, use 4 mm², not 2.5 mm².
• Common equivalents: 18 AWG ≈ 0.75 mm², 16 AWG ≈ 1.5 mm² (slightly less, 1.31 mm²), 10 AWG ≈ 6 mm² (slightly less, 5.26 mm²), 4 AWG ≈ 25 mm² (21.2 mm²).
• Speaker cable: 16 AWG (1.5 mm²) is fine for most home speakers up to about 15 m; use 14 AWG (2.5 mm²) for longer runs.
• Cheap cables can be undersized: some budget cables use copper-clad aluminum (CCA), which has about 60% more resistance than copper.
• Check the insulation markings: quality cables print the size (for example “3 × 1.5 mm²” or “12 AWG”) along the jacket.

Frequently asked questions