AWG 20 Wire

Diameter 0.0320″
Millimeters 0.813 mm
Cross-section 1,024 cmil
mm² 0.5189

Nominal bare-conductor dimensions per ASTM B258. AWG is geometric: d = 0.005 × 92(36−n)/39 in with n = 20; 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 20
18 0.0403″ 1.024 +0.0083″
19 0.0359″ 0.912 +0.0039″
20 0.0320″ 0.813
21 0.0285″ 0.724 −0.0035″
22 0.0253″ 0.643 −0.0067″

Measuring sheet metal, not wire? Sheet uses a different gauge scale — see 20 gauge sheet (steel: 0.0359″).

Data provenance. ASTM B258, Standard Specification for Nominal Diameters of AWG Sizes (ASTM International). See all data sources.