Wire & voltage

AWG to mm² Calculator

AWG diameter follows the standard logarithmic gauge relationship, and area equals pi times diameter squared divided by four. Metric area can be compared with the nearest nominal AWG geometry.

Convert American Wire Gauge to diameter, cross-sectional area, and circular mils, or find the nearest AWG for a metric area.

Calculated result

Conductor geometry

Calculating…

Calculated locally in your browser

Planning math only. Verify equipment specifications and installation requirements separately.

AWG to mm² Calculator relationship diagram. The illustration supports the text result; it is not a wiring or installation drawing.

What this calculator returns

Metric conductors are not exact ampacity equivalents. Use the nearest-size result as a geometry reference only.

Formula and variables

The calculation runs entirely in your browser. Static formulas, definitions, examples, and tables remain readable without JavaScript.

Formula

Diameter(in) = 0.005 × 92^((36 - n)/39); area = πd²/4; circular mils = diameter(mils)².

Vdrop: Voltage lost across the conductor path, in volts.
I: Current through the conductor, in amperes.
R: Electrical resistance of the modeled conductor path, in ohms.
ρ: Material resistivity at the modeled temperature, in ohm-metres.
L: Conductor length used by the selected path model.
A: Metal cross-sectional area of the conductor.

n is the AWG gauge number, with 0, 00, 000, and 0000 represented by indices 0 through -3.

Worked example

Worked example inputs
Input	Value
Conversion direction	AWG to metric
AWG size	12 AWG
Metric area	2.5 mm²

12 AWG has a calculated diameter of about 2.053 mm and a cross-sectional area of about 3.309 mm².

Reference table

Calculated conductor resistance by AWG, material, and temperature. Values use the AWG geometry equation and the resistivity constants documented on Sources; they are not copied from an electrical code table.
AWG	Cu 20°C Ω/1000 ft	Cu 75°C Ω/1000 ft	Al 20°C Ω/1000 ft	Al 75°C Ω/1000 ft	Cu 20°C Ω/km	Al 20°C Ω/km
14	2.5254	3.0712	4.1400	5.0576	8.2853	13.5825
12	1.5882	1.9315	2.6036	3.1807	5.2107	8.5421
10	0.9988	1.2147	1.6374	2.0004	3.2770	5.3722
8	0.6282	0.7640	1.0298	1.2581	2.0609	3.3786
6	0.3951	0.4805	0.6476	0.7912	1.2961	2.1248
4	0.2485	0.3022	0.4073	0.4976	0.8152	1.3363

Frequently asked questions

How is AWG diameter calculated?

The calculator uses the standard logarithmic AWG diameter relationship and derives cross-sectional area from that diameter.

Does insulation change the AWG area?

No. AWG describes conductor geometry; insulation and stranding affect outside diameter and construction, not the nominal AWG area shown here.

Is 2.5 mm² exactly the same as 12 AWG?

No. The calculator shows geometric area and the nearest nominal AWG; standards and construction differ.

Assumptions and limitations

Solid-wire nominal geometry is calculated from the AWG relationship.
Stranding and insulation change physical outside diameter.
No ampacity equivalence is claimed.

Method and sources

Review the AWG reference, calculation methodology, and standards status for the references most relevant to this calculation. The broader technical sources index records source scope and verification. Last reviewed 2026-08-13.