Sheet Metal Thickness Standards & Gauge Charts

In sheet metal fabrication, thickness can be specified in two ways: as an exact measurement in millimeters or inches or using a gauge system. The gauge system, however, follows a different scale that isn’t linear. Metals gauges are standard numbers developed by measuring the thickness of sheet metal in relation to its weight per square foot.

Gauge System for Sheet Metal

Unlike standard metric measurement systems, where sheet thickness is indicated directly in mm, gauge numbers represent thickness based on historical drawing operations. This means a lower gauge number corresponds to a thicker sheet, while a higher one indicates a thinner sheet. For example, 3-gauge sheet metal is about 6.07 mm (0.2391 inches) thick, while 38-gauge sheet metal is only 0.15 mm (0.0060 inches) thick. In many regions, sheet metal over 6 mm is considered a plate rather than a sheet.

Different sheet metal gauges are recommended for specific applications. Choose wisely during the design phase. For example, a 10 ga metal sheet (3.4 mm or 0.1345 inches) would be ideal for heavy-duty applications, such as structural components.

The next section highlights gauge tables of the most commonly used sheet metal materials.

Standard Steel Gauge Chart

Gauge	Thickness (in)	Thickness (mm)
3	.239	6.073
4	.224	5.695
5	.209	5.314
6	.194	4.935
7	.179	4.554
8	.164	4.176
9	.150	3.797
10	.135	3.416
11	.120	3.038
12	.105	2.657
13	.090	2.278
14	.075	1.897
15	.067	1.709
16	.060	1.519
17	.054	1.367
18	.048	1.214
19	.042	1.062
20	.036	0.912
21	.033	0.836
22	.030	0.759
23	.027	0.683
24	.024	0.607
25	.021	0.531
26	.018	0.455
27	.016	0.417
28	.015	0.378
29	.014	0.343
30	.012	0.305
31	.011	0.267
32	.010	0.246
33	.009	0.229
34	.008	0.208
35	.008	0.191
36	.007	0.170
37	.006	0.163
38	.006	0.152

Galvanized Steel Gauge Chart

Gauge	Thickness (in)	Thickness (mm)
8	.168	4.270
9	.153	3.891
10	.138	3.510
11	.123	3.132
12	.108	2.753
13	.093	2.372
14	.079	1.994
15	.071	1.803
16	.064	1.613
17	.058	1.461
18	.052	1.311
19	.046	1.158
20	.040	1.006
21	.037	0.930
22	.034	0.853
23	.031	0.777
24	.028	0.701
25	.025	0.627
26	.022	0.551
27	.020	0.513
28	.019	0.475
29	.017	0.437
30	.016	0.399
31	.014	0.361
32	.013	0.340

Stainless Steel Gauge Chart

Gauge	Thickness (in)	Thickness (mm)
00000000	.500	12.700
000000	.469	11.902
00000	.438	11.113
0000	.406	10.320
000	.375	9.525
00	.344	8.733
0	.313	7.938
1	.281	7.145
2	.266	6.746
3	.250	6.350
4	.234	5.954
5	.219	5.555
6	.203	5.159
7	.188	4.763
8	.172	4.366
9	.156	3.967
10	.141	3.571
11	.125	3.175
12	.109	2.779
13	.094	2.380
14	.078	1.984
15	.070	1.786
16	.063	1.588
17	.056	1.427
18	.050	1.270
19	.044	1.110
20	.038	0.953
21	.034	0.874
22	.031	0.792
23	.028	0.714
24	.025	0.635
25	.022	0.556
26	.019	0.475
27	.017	0.437
28	.016	0.396
29	.014	0.358
30	.013	0.318
31	.011	0.277
32	.010	0.259
33	.009	0.239
34	.009	0.218
35	.008	0.198
36	.007	0.178
37	.007	0.168
38	.006	0.157

Carbon Steel Gauge Chart

Gauge	Thickness (in)	Thickness (mm)
3	.239	6.07
4	.224	5.69
5	.209	5.31
6	.194	4.94
7	.179	4.55
8	.164	4.18
9	.149	3.80
10	.134	3.42
11	.120	3.04
12	.105	2.66
13	.090	2.28
14	.075	1.90
15	.067	1.71
16	.060	1.52
17	.054	1.37
18	.048	1.21
19	.042	1.06
20	.036	0.91
21	.033	0.84
22	.030	0.76
23	.027	0.68
24	.024	0.61
25	.021	0.53
26	.018	0.45
27	.016	0.42
28	.015	0.38
29	.013	0.34
30	.012	0.30

Aluminium Sheet Gauge Chart

Gauge	Thickness (in)	Thickness (mm)
6	.162	4.115
7	.144	3.665
8	.129	3.264
9	.114	2.906
10	.102	2.588
11	.091	2.304
12	.081	2.052
13	.072	1.829
14	.064	1.628
15	.057	1.450
16	.051	1.290
17	.045	1.151
18	.040	1.024
19	.036	0.912
20	.032	0.813
21	.028	0.724
22	.025	0.643
23	.023	0.574
24	.02	0.511
25	.018	0.455
26	.017	0.404
27	.0142	0.361
28	.013	0.320
29	.011	0.287
30	.010	0.254

Zinc Sheet Gauge Chart

Gauge	Thickness (in)	Thickness (mm)
1	.002	0.051
2	.004	0.102
3	.006	0.152
4	.008	0.203
5	.010	0.254
6	.012	0.305
7	.014	0.356
8	.016	0.406
9	.018	0.457
10	.020	0.508
11	.024	0.610
12	.028	0.711
13	.032	0.813
14	.036	0.914
15	.040	1.016
16	.045	1.143
17	.050	1.270
18	.055	1.397
19	.060	1.524
20	.070	1.778
21	.080	2.032
22	.090	2.286
23	.100	2.540
24	.125	3.175
25	.250	6.350
26	.375	9.525
27	.500	12.700
28	1.000	25.400

Copper Sheet Gauge Chart

Gauge	Thickness (in)	Thickness (mm)
7	.180	4.572
8	.165	4.191
9	.148	3.759
10	.134	3.404
11	.120	3.048
12	.109	2.769
14	.083	2.108
16	.065	1.651
18	.049	1.245
20	.035	0.889
22	.028	0.711
24	.022	0.559
26	.018	0.457
28	.014	0.356
30	.012	0.305

Brass Sheet Gauge Chart

Gauge	Thickness (in)	Thickness (mm)
7	.144	3.665
8	.129	3.264
9	.114	2.906
10	.102	2.588
11	.091	2.305
12	.081	2.053
14	.064	1.628
16	.051	1.291
18	.040	1.024
20	.032	0.812
22	.025	0.644
24	.020	0.511
26	.016	0.405
28	.013	0.321
30	.010	0.255

Sheet Metal Thickness & Gauges: Quick Reference Chart

To make it easier for engineers and designers, we’ve compiled all gauge conversions into a single downloadable reference chart.

Download The Quick Reference Chart

Frequently Asked Questions

Are There Gauge Limitations for Specific Metal Types?

Yes. There is a limit on how thin a sheet metal can get before it becomes unusable. Most sheet metals have a lower limit of 0.5 mm and a higher limit of 6 mm, but this depends on the material type.

Does Gauge Affect Corrosion Resistance?

Yes and no. A thicker gauge does not mean the sheet metal is more corrosion-resistant. It only implies that the material will take longer to corrode, making it more durable than a thinner gauge metal.

Why Are Gauges Different for Different Metals?

Material gauge is a subject of its density. Gauge size is based on the weight of the sheet metal, which is different for each material type.

What Thickness Limit Classifies Metal as Being a Sheet?

The lower limit (the thinnest a sheet metal can be) is 0.5 mm, and the upper limit (the thickest a sheet metal can be) is 6 mm. Any metal thicker than 6 mm is no longer a sheet metal but a metal plate. However, these limits can vary from region to region.

Next Steps for Sheet Metal Fabrication Success

Making an informed decision regarding sheet metal thickness reduces waste and production costs. Before deciding on the sheet metal gauge chart to use, consider the application, material type, environmental factors, industry standards, weight, and budget. The chosen sheet metal gauge should give high performance, and the right gauge chart should be used.

Need Precision-Cut Sheet Metal Parts? If you have a sheet metal project and need high-quality cutting and bending services, Xometry offers on-demand manufacturing with a wide range of materials, thicknesses, and finishes. Get an instant quote today and bring your designs to life with expert fabrication.