Sheet & Plate

Sheet Metal Gauge Chart

Gauge is not a unit. The same number means a different thickness in every material, and the gap is wide enough to ruin a part if you order from the wrong column.

16 gauge is 0.0598″ in steel, 0.0635″ galvanized, 0.0625″ stainless and 0.0508″ in aluminum — a 20% spread across four materials with the same label.

Sheet metal gauge to thickness for steel, galvanized, stainless and aluminum

7	0.1793	0.0000	0.1875	0.1443	0.0000	7.322
8	0.1644	0.1681	0.1719	0.1285	0.0037	6.714
9	0.1495	0.1532	0.1563	0.1144	0.0037	6.105
10	0.1345	0.1382	0.1406	0.1019	0.0037	5.493
11	0.1196	0.1233	0.1250	0.0907	0.0037	4.884
12	0.1046	0.1084	0.1094	0.0808	0.0038	4.272
13	0.0897	0.0934	0.0938	0.0720	0.0037	3.663
14	0.0747	0.0785	0.0781	0.0641	0.0038	3.051
15	0.0673	0.0710	0.0703	0.0571	0.0037	2.748
16	0.0598	0.0635	0.0625	0.0508	0.0037	2.442
17	0.0538	0.0575	0.0563	0.0453	0.0037	2.197
18	0.0478	0.0516	0.0500	0.0403	0.0038	1.952
19	0.0418	0.0456	0.0438	0.0359	0.0038	1.707
20	0.0359	0.0396	0.0375	0.0320	0.0037	1.466
21	0.0329	0.0366	0.0344	0.0285	0.0037	1.344
22	0.0299	0.0336	0.0313	0.0253	0.0037	1.221
23	0.0269	0.0306	0.0281	0.0226	0.0037	1.099
24	0.0239	0.0276	0.0250	0.0201	0.0037	0.976
25	0.0209	0.0247	0.0219	0.0179	0.0038	0.854
26	0.0179	0.0217	0.0188	0.0159	0.0038	0.731
27	0.0164	0.0202	0.0172	0.0142	0.0038	0.670
28	0.0149	0.0187	0.0156	0.0126	0.0038	0.608
29	0.0135	0.0172	0.0141	0.0113	0.0037	0.551
30	0.0120	0.0157	0.0125	0.0100	0.0037	0.490

Gauges 7–30 (galvanized from 8). Lower gauge = thicker material.

Aluminum is the odd one out — and it is computable

Steel and stainless gauges are weight-based standards that must be looked up. Aluminum sheet gauge is the AWG (Brown & Sharpe) wire system, which means it comes from a formula:

thickness = 0.005 × 92^((36 − gauge) / 39)  inch

Running that formula against published aluminum catalog values agrees to within 0.19% across the whole range — which is how the numbers in that column were verified. No other material on this page works that way.

Galvanized is thicker than the steel underneath it

A galvanized sheet is base steel plus zinc on both faces. The coating adds a consistent ~0.0037″ from gauge 8 to 30 — so 16 ga galvanized (0.0635″) is 16 ga steel (0.0598″) plus zinc, not a different steel thickness. If a drawing calls out base metal thickness, that difference is yours to account for.

These are nominal thicknesses. Delivered sheet varies within the mill tolerance of its standard — ASTM A480 for stainless, ASTM A568 for carbon steel sheet. For anything where fit or bend allowance matters, measure the actual sheet rather than working from the gauge number. Galvanized is listed from 8 ga up; lighter galvanized gauges are not part of the standard table.

Data source and method

Steel: Manufacturers' Standard Gauge for Sheet Steel (MSG).
Galvanized: ASTM A653, G90 coating.
Stainless: ASTM A480.
Aluminum: Computed from the Brown & Sharpe / AWG formula, cross-checked against published catalog values (max deviation 0.19%).
Verification: Spot-checked against mill catalog values: steel 16 ga 0.0598″, 11 ga 0.1196″; galvanized 16 ga 0.0635″; stainless 16 ga 0.0625″. Aluminum is independently cross-checked by formula (max deviation 0.19%), which also validates the transcription of the other columns' source data.
Derived: Millimetre and lb/ft² values calculated from thickness × density (steel 0.2836, stainless 0.2894, aluminum 0.0975 lb/in³).

Related charts

AWG wire size chart — the same Brown & Sharpe numbering that aluminum sheet gauge uses
Drill bit size chart — for pilot and clearance holes in sheet