Why Two Systems Exist
American Wire Gauge numbers run backwards: a larger AWG number is a thinner conductor. Metric specifications state either the conductor diameter in millimetres or the cross-sectional area in mm². Datasheets mix all three, which is where procurement errors start.
Conversion Table
| AWG | Diameter (mm) | Area (mm²) | Commonly seen in |
|---|---|---|---|
| 28 | 0.321 | 0.081 | Stranded patch cord conductors |
| 26 | 0.405 | 0.129 | Slim patch cords |
| 24 | 0.511 | 0.205 | CAT5e bulk cable |
| 23 | 0.573 | 0.258 | CAT6 and CAT6A bulk cable |
| 22 | 0.644 | 0.326 | Alarm and security cable |
| 20 | 0.812 | 0.518 | Signal and speaker cable |
| 18 | 1.024 | 0.823 | Speaker cable, low-voltage power |
| 16 | 1.291 | 1.31 | Speaker cable, appliance leads |
| 14 | 1.628 | 2.08 | Building wire |
| 12 | 2.053 | 3.31 | Building wire |
Reading A Cable Specification
- A stated AWG applies to the conductor, not the finished cable diameter
- Stranded conductors of the same AWG have a larger overall diameter than solid
- Cross-sectional area is what determines resistance, not the gauge number
- Where a datasheet gives only a diameter, check whether it is the conductor or the insulated core
The Practical Check
If a conductor size is critical to your design — a PoE budget, a voltage drop calculation, a regulatory cross-section — ask for the DC loop resistance rather than the gauge. Resistance is measurable on arrival; a printed gauge number is not.
Applying this to a live project? Send the specification and we will tell you how it lands for your case — awg to millimetre conductor reference is exactly the kind of question we answer whether or not there is an order attached.
