AWG to mm²
Every figure here is the AWG geometry worked out with a calculator — a diameter turned into an area. It is a size conversion only, and says nothing about what current a conductor may carry; that is governed by your code book and the conditions of the run.
Enter a gauge and the tool gives you the conductor diameter, the metric cross-section in mm², and the North American kcmil figure. Enter an area in the second box instead and it reports the gauge that lands closest — useful when a European spec quotes only mm².
Worked example
For 12 AWG, n = 12, so the diameter is 0.005 × 92^((36 − 12) ÷ 39) = 0.005 × 92^(0.615) ≈ 0.0808 in, which is about 2.05 mm. The area is π × (2.05 ÷ 2)² ≈ 3.31 mm². That same diameter is 80.8 mils, so the area is 80.8² ÷ 1000 ≈ 6.53 kcmil.
The formula
d(in) = 0.005 × 92^((36 − n) ÷ 39) · area = π × (d ÷ 2)²
AWG is defined, not tabulated: 36 gauge is fixed at 5 thousandths of an inch, 0000 at 0.46 inch, and each of the 40 steps between multiplies the diameter by the same ratio, the 39th root of 92. Because the sizes follow a rule, this page computes them from the rule rather than storing a gauge chart.
Questions
- How do I convert AWG to mm²?
- Work out the wire diameter from the gauge, then take the area of that circle. American Wire Gauge is a geometric series: the diameter in inches is 0.005 × 92^((36 − n)/39). Turn that into millimetres, and the area is π × (d ÷ 2)². This tool runs the whole chain from the gauge number you enter.
- What is the formula behind the gauge numbers?
- Every step in AWG multiplies the diameter by the same ratio, the 39th root of 92. Number 36 is pinned at 0.005 inch and number 0000 at 0.46 inch, and the 40 sizes between are geometric steps. Because it is a formula and not a chart, the tool computes each size rather than looking it up.
- How do I enter the big sizes like 4/0?
- Type them as they are written — 1/0, 2/0, 3/0 and 4/0, or the zero forms 0, 00, 000 and 0000. Internally those are gauge numbers 0, −1, −2 and −3, and the same formula covers them, so 4/0 comes out at about 107 mm².
- What is a kcmil and why is it shown?
- A circular mil is the area of a circle one mil (a thousandth of an inch) across, and a kcmil is a thousand of them — the unit North American conductors above 4/0 are sized in. It is simply the diameter in mils, squared, divided by 1000, so the tool reports it alongside the mm² figure.
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