9 Gauge Sheet Metal

Steel (MSG) 0.1495″

Galvanized 0.1532″

Stainless 0.1562″

Aluminum 0.1144″

Steel: 3.80 mm · Galvanized: 3.89 mm · Stainless: 3.97 mm · Aluminum: 2.91 mm . The same gauge number is a different thickness in each material — always confirm which scale a drawing means, or better, specify decimal thickness.

Neighboring gauges (steel column)

Gauge	Steel	Galvanized	Stainless	Aluminum
7	0.1793	—	0.1875	0.1443
8	0.1644	0.1681	0.1719	0.1285
9	0.1495	0.1532	0.1562	0.1144
10	0.1345	0.1382	0.1406	0.1019
11	0.1196	0.1233	0.1250	0.0907

Measuring wire, not sheet? Wire uses the AWG scale — see AWG 9 (0.1144″ Ø). Aluminum sheet happens to share the AWG scale, which is why the aluminum column matches it.

Data provenance. Sheet-metal gauge tables: Manufacturers’ Standard Gauge (steel), galvanized, and stainless (Industry reference). ASTM B258, Standard Specification for Nominal Diameters of AWG Sizes (ASTM International). Steel per Manufacturers' Standard Gauge; stainless per the conventional supplier table (no governing standard); aluminum per B&S (= AWG, ASTM B258). Sheets carry rolling tolerances. See all data sources.