AWG 21 Wire
Diameter 0.0285″
Millimeters 0.724 mm
Cross-section 812 cmil
mm² 0.4116
Nominal bare-conductor dimensions per ASTM B258. AWG is geometric: d = 0.005 × 92(36−n)/39 in with n = 21; area is derived from the diameter. Ampacity depends on insulation, bundling, and the electrical code in force — it is a property of the installation, not the gauge.
Neighboring gauges
| AWG | Diameter | mm | vs AWG 21 |
|---|---|---|---|
| 19 | 0.0359″ | 0.912 | +0.0074″ |
| 20 | 0.0320″ | 0.813 | +0.0035″ |
| 21 | 0.0285″ | 0.724 | — |
| 22 | 0.0253″ | 0.643 | −0.0032″ |
| 23 | 0.0226″ | 0.574 | −0.0059″ |
Measuring sheet metal, not wire? Sheet uses a different gauge scale — see 21 gauge sheet (steel: 0.0329″).