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

Galvanized gauge runs a consistent ~0.0037″ thicker than bare steel from gauge 8 to 30 — 16 ga galvanized is 0.0635″ against 16 ga steel at 0.0598″. It is tempting to call that difference "the zinc," but it is about 2.3× what a G90 coating actually adds (0.90 oz/ft² two-sided is roughly 0.0016″), so it is not base steel plus a known coating class. Treat it as what it is: the published galvanized gauge value. If a drawing calls out base metal thickness, that difference is still 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.

Take the table with you — CSV · JSON

Data source and method

Steel: Manufacturers' Standard Gauge for Sheet Steel (MSG).
Galvanized: ASTM A653 galvanized sheet gauge table. Coating class is deliberately not asserted — the gauge-to-gauge difference does not match any single class. See the section above.
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 across all gauges (max deviation 0.19%). The steel, galvanized and stainless columns are transcribed standard values, not computed — the aluminum check does not validate them, and only the four figures listed above were spot-checked.
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