AWG Conversion Calculator

Convert American Wire Gauge to and from square millimetres, circular mils, kcmil and conductor diameter. Enter a value in any unit to see all the others, plus the nearest standard gauge.

For AWG, enter a gauge such as 10 or 4/0.

How It Works

The AWG formula

American Wire Gauge is geometric. The conductor diameter for gauge n is:

diameter (in) = 0.005 × 92(36 - n) / 39

Gauges 1/0 to 4/0 use n = 0, -1, -2, -3. The cross-sectional area in circular mils is the diameter in mils squared, and 1 circular mil is 5.067 × 10-4 mm².

Worked example

10 AWG: diameter = 0.005 × 9226/39 ≈ 0.1019 in (2.59 mm), which is 101.9² ≈ 10,380 circular mils, or about 5.26 mm².

AWG Wire Chart: Size, Area and Ampacity

Each AWG size with its metric area, circular mils, conductor diameter, and the allowable ampacity of copper and aluminium at 60, 75 and 90°C terminations.

American Wire Gauge sizes with cross-sectional area, diameter and NEC 310.16 ampacity
AWG mm² Circular mils Diameter (mm) Copper ampacity (A) Aluminium ampacity (A)
60°C 75°C 90°C 60°C 75°C 90°C
14 2.08 4,110 1.63 15 20 25 — — —
12 3.31 6,530 2.05 20 25 30 — — —
10 5.26 10,380 2.59 30 35 40 — — —
8 8.37 16,510 3.26 40 50 55 30 40 45
6 13.30 26,240 4.12 55 65 75 40 50 55
4 21.15 41,740 5.19 70 85 95 55 65 75
3 26.67 52,620 5.83 85 100 110 65 75 85
2 33.62 66,360 6.54 95 115 130 75 90 100
1 42.41 83,690 7.35 110 130 145 85 100 115
1/0 53.49 105,600 8.25 125 150 170 100 120 135
2/0 67.43 133,100 9.27 145 175 195 115 135 150
3/0 85.01 167,800 10.40 165 200 225 130 155 175
4/0 107.20 211,600 11.68 195 230 260 150 180 205

Ampacities are NEC 310.16 values for not more than three current-carrying conductors in a raceway at 30°C ambient, before any derating. Aluminium is not commonly made below 8 AWG, hence the gaps. Areas are nominal solid-conductor values; stranded conductors of the same AWG have a slightly larger overall diameter. To size a conductor for a specific load, use the wire size calculator.

Frequently Asked Questions

How do I convert AWG to mm²?

Find the conductor diameter from the AWG formula, square it to get circular mils, then multiply by 0.0005067 to get mm². For example 10 AWG is about 5.26 mm².

What is a circular mil?

A circular mil is the area of a circle one mil (0.001 in) in diameter. The area of a round conductor in circular mils is simply its diameter in mils, squared.

What does 4/0 mean?

Sizes larger than 1 AWG are written 1/0, 2/0, 3/0 and 4/0 (spoken "one aught" to "four aught"). Above 4/0, conductors are sized in kcmil instead.

Why does a smaller AWG number mean a bigger wire?

AWG counts drawing steps: each step down in gauge number is a larger diameter. So 10 AWG is bigger than 14 AWG.

How is kcmil related to AWG?

kcmil is thousands of circular mils, used for conductors larger than 4/0. For example 250 kcmil is just larger than 4/0 (about 212 kcmil).

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