AWG to circular mil / kcmil converter

Convert wire size between AWG and circular mils / kcmil — the American unit cable and terminal specs are written in — plus diameter and mm².

AWG → circular mil

Enter a gauge — whole or half sizes, or 0000 / 4/0 style — and read the cross-section US cable and terminal specs reference.

AWG size

Diameter (mil): 257.6
Diameter (in): 0.2576
Diameter (mm): 6.54
Area (CM): 66,371
Area (kcmil): 66.4
Area (mm²): 33.63

kcmil → AWG

Enter a size in kcmil (formerly MCM) — the unit large power conductors are quoted in.

Area (kcmil)

Equivalent AWG: --

Quick reference

Nominal circular-mil areas from the standard gauge formula.

Gauge	Diameter (mil)	Area (kcmil)
4/0	460	211.6
2/0	364.8	133.08
1/0	324.9	105.53
2 AWG	257.6	66.37
4 AWG	204.3	41.74
6 AWG	162	26.25
8 AWG	128.5	16.51
10 AWG	101.9	10.38
12 AWG	80.8	6.53
14 AWG	64.1	4.11

kcmil was formerly called MCM. Values are nominal for bare conductor; finished crimp barrels and lugs use their own stamped sizes.

Browse related parts:

power cable crimp terminals busbars

Frequently asked questions

How do you convert AWG to circular mils?

Conductor diameter in mils follows d(mil) = 5 × 92^((36 − AWG) / 39), and area in circular mils is CM = d². For example, 12 AWG works out to about 6,530 CM (6.5 kcmil). kcmil is just CM ÷ 1,000.

What is a circular mil and why do cable specs use it?

A circular mil is the area of a circle one mil (0.001 inch) in diameter, so area equals the square of the diameter in mils. US cable and terminal specs quote cross-section in CM or kcmil because it avoids the π factor — CM = d², with no multiplication needed.

How do I convert kcmil back to an AWG size?

The calculator inverts the gauge formula: from a kcmil value it computes d(mil) = √(kcmil × 1,000), then AWG = 36 − 39 × ln(d/5) / ln(92), rounded to the nearest whole gauge. Sizes above 4/0 (2,116 CM) are usually quoted in kcmil instead of a gauge number.

How it works

IC Source Direct converts between gauge and cross-section the same way US cable and terminal specs do. Conductor diameter follows d(mil) = 5 × 92^((36 − AWG) / 39), and a wire one mil in diameter has an area of exactly one circular mil, so CM = d². kcmil is simply thousands of circular mils (formerly MCM), the standard unit for large power conductors, and 1 circular mil equals π/4 × 10⁻⁶ sq in ≈ 0.0005067 mm². Values shown are for bare conductor — finished crimp barrels and lugs add their own dimensions.

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