You may have seen our list of standard materials which are part of our online quoting system. But for many of our customers involved in making jewelry, fine art, or interior design, these materials aren't what they're looking for.  For them (and anyone who wants a material not on the list) we do custom orders. Popular materials in these fields include copper, brass, and silver. On these projects, the thickness of the material is frequently specified in gauge, rather than inches or millimeters.

In an earlier article, we took a look at the standard gauges for steel sheet. Gauge when applied to copper, brass, or silver means a different set of thicknesses, however. It's based on the American or Brown and Sharpe Wire Gauge standard. As with steel, as the gauge gets higher, the thickness gets lower. Unlike with steel, I can't find a set standard for tolerances for sheets of this material. This means that you're at the mercy of the manufacturer and distributor for tolerances here. (If you know of such a standard, please let me know.)

Here's a chart showing wire gauges in inches and millimeters.

Copper, Brass, Silver, etc. Gauge	Thickness, Inches	Thickness, mm
8	0.1285	3.264
9	0.1144	2.906
10	0.1019	2.588
11	0.0907	2.305
12	0.0808	2.053
13	0.072	1.828
14	0.0641	1.628
15	0.0571	1.45
16	0.0508	1.291
17	0.0453	1.15
18	0.0403	1.024
19	0.0359	0.912
20	0.032	0.812
21	0.0285	0.723
22	0.0253	0.644
23	0.0226	0.573
24	0.0201	0.511
25	0.0179	0.455
26	0.0159	0.405
27	0.0142	0.361
28	0.0126	0.321
29	0.0113	0.286
30	0.01	0.255

Also, galvanized steel sheet also has its own set of gauge thicknesses:

Galvanized Gauge	Thickness, inches	Thickness, mm
10	0.1345	3.4163
11	0.1196	3.03784
12	0.1046	2.65684
13	0.0897	2.27838
14	0.0747	1.89738
15	0.0673	1.70942
16	0.0598	1.51892
17	0.0538	1.36652
18	0.0478	1.21412
19	0.0418	1.06172
20	0.0359	0.91186
21	0.0329	0.83566
22	0.0299	0.75946
23	0.0269	0.68326
24	0.0239	0.60706
25	0.0209	0.53086
26	0.0179	0.45466
27	0.0164	0.41656
28	0.0149	0.37846
29	0.0135	0.3429
30	0.012	0.3048
31	0.0105	0.2667
32	0.0097	0.24638

Zinc sheet has yet another gauge system for thickness. I can't recall a single customer who ever wanted us to make something out of zinc sheet, so I'll leave that for you to find on your own. Machinery's Handbook is an authoritative source, and has a chart which includes zinc sheet gauges.

If you're having trouble picking out a thickness, take a look at our page on deciding on a material thickness.

Finally, keep in mind that some manufacturers, distributors, and end users get the gage thickness wrong. They might use the wrong metal's gauge chart or pick an obsolete standard when labeling a sheet of material. That's why we suggest working with thicknesses in common, unambiguous units like millimeters or inches.