AWG 18 Wire
Diameter 0.0403″
Millimeters 1.024 mm
Cross-section 1,624 cmil
mm² 0.8229
Nominal bare-conductor dimensions per ASTM B258. AWG is geometric: d = 0.005 × 92(36−n)/39 in with n = 18; 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 18 |
|---|---|---|---|
| 16 | 0.0508″ | 1.290 | +0.0105″ |
| 17 | 0.0453″ | 1.151 | +0.0050″ |
| 18 | 0.0403″ | 1.024 | — |
| 19 | 0.0359″ | 0.912 | −0.0044″ |
| 20 | 0.0320″ | 0.813 | −0.0083″ |
Measuring sheet metal, not wire? Sheet uses a different gauge scale — see 18 gauge sheet (steel: 0.0478″).