Workshop and Metalwork Calculators
AWG to mm.
Pick an AWG size to see the solid-wire diameter in millimetres and inches and the cross-section in mm2 and circular mils. Or type a measured diameter to find the nearest AWG. Runs in your browser; nothing is sent or stored.
Inputs
Result
Fill the form and press Calculate.
Answer first. AWG diameter = 0.127 mm x 92^((36 - n) / 39). 12 AWG is 2.053 mm across and 3.31 mm2 in section; 10 AWG is 2.588 mm and 5.26 mm2.
Worked example
12 AWG: d = 0.127 mm x 92^((36 - 12) / 39) = 2.053 mm (0.0808 in). Cross-section = pi/4 x d2 = 3.31 mm2, or 6,530 circular mils. That matches the published table value of 2.053 mm for 12 AWG.
How it works
Formula. By definition 36 AWG is 0.005 in (0.127 mm) and 0000 AWG is 0.46 in (11.68 mm). With 39 steps between them the diameter is d = 0.127 mm x 92^((36 - n)/39), where n is the AWG number; 00, 000 and 0000 count as n = -1, -2 and -3. Each step toward a smaller number multiplies the diameter by about 1.1229.
Solid wire. The diameter and area apply to a single solid round conductor. Stranded wire of the same AWG has the same copper area but a slightly larger overall diameter because of the gaps between strands.
Reverse lookup. Enter a measured bare-wire diameter and the tool solves n = 36 - 39 x ln(d / 0.127) / ln 92, then shows the nearest whole gauge. Measure bare metal, not the insulation.
Safety. This is a size conversion, not a current rating. Do not choose a wire for a circuit from its diameter alone; use an ampacity chart and your local electrical code, or ask a licensed electrician.
Sources
- American wire gauge - Wikipedia (opened 2026-10-08)
The definition points and the diameter formula are from the page above; results match its published table for 10 and 12 AWG. Circular mils are the diameter in mils squared.
FAQ
What is 12 AWG in mm?
2.053 mm in diameter, with a cross-section of 3.31 mm2.
What AWG is 2.5 mm2?
2.5 mm2 is not a whole AWG size. Its diameter is 1.78 mm, which falls between 14 AWG (2.08 mm2) and 13 AWG (2.63 mm2); the reverse lookup shows 13 AWG as nearest. Enter 1.78 mm in the reverse lookup to check.
Does a bigger AWG number mean thicker wire?
No, the opposite. Higher AWG numbers are thinner wire; 0000 is the thickest listed here and 40 the thinnest.
What are circular mils?
The area of a circle measured in mils squared, where a mil is 0.001 in. For a round wire it equals the diameter in mils squared.
Is stranded wire the same size?
The AWG number refers to the equivalent solid copper area. Stranded wire is slightly thicker overall.