Sheet Metal Gauge Chart

When working with sheet metal, you often hear the term “gauge.” For those not familiar with this system, it can be unclear what a specific gauge, like 18 gauge steel, actually means. In this blog, we’ll explain the gauge system and include a helpful sheet metal gauge chart to make it easier to understand.

What is the Gauge System?

The gauge system is a way to measure and categorize the thickness of sheet metal. In this system, a higher gauge number means a thinner sheet of metal. For example, 18 gauge steel is thicker than 22 gauge steel. This system helps standardize thickness measurements, making it easier to choose the right metal for your project.

How Are Sheet Metal Gauges Used?

Gauges specify the thickness of sheet metal but are neither standard nor metric measurements. Instead, a gauge conversion chart is used to determine the actual thickness in inches or millimeters. For instance, 18 gauge steel is 0.0478 inches or 1.214 millimeters thick according to a gauge chart. The number “18” itself does not directly relate to these measurements.

There are various gauge systems for different metals. For example, 18 gauge steel has a thickness of 0.0478 inches, while 18 gauge aluminum measures 0.0403 inches thick. Due to these differences, always refer to a gauge chart to ensure the metal’s thickness meets the required specifications.

History of the Gauge System

The gauge system has a long history in metal fabrication, originating from the British wire industry before standard and metric systems were common. Initially, it described the diameter of metal wires. Over time, it has become a widely used method for indicating the thickness of both wire and sheet metal. This system remains popular due to its historical significance and practicality in the metal fabrication industry.

Sheet Metal Gauge Charts

Mild Steel Gauge Chart
Gauge Number	Inches	MM
7	.1793	4.554
8	.1644	4.175
9	.1495	3.797
10	.1345	3.416
11	.1196	3.038
12	.1046	2.656
14	.0747	1.897
16	.0598	1.518
18	.0478	1.214
20	.0359	.911
22	.0299	.759
24	.0239	.607
26	.0179	.454
28	.0149	.378

Aluminum Gauge Chart*
Gauge Number	Inches	MM
7	.1443	3.665
8	.1285	3.264
9	.1144	2.906
10	.1019	2.588
11	.09074	2.305
12	.08081	2.053
14	.06408	1.628
16	.05082	1.291
18	.04030	1.024
20	.03196	.812
22	.02535	.644
24	.02010	.511
26	.01594	.405
28	.01264	.321
30	.01003	.255

Stainless Steel Gauge Chart*
Gauge Number	Inches	MM
8	.17187	4.365
9	.15625	3.968
10	.14062	3.571
11	.125	3.175
12	.10937	2.778
14	.07812	1.984
16	.0625	1.587
18	.050	1.270
20	.0375	.9525
22	.03125	.7937
24	.025	.635
26	.01875	.476
28	.01562	.396
30	.0125	.3175

Galvanized Steel Gauge Chart*
Gauge Number	Inches	MM
8	.1681	4.269
9	.1532	3.891
10	.1382	3.510
11	.1233	3.1318
12	.1084	2.753
14	.0785	1.9939
16	.0635	1.6129
18	.0516	1.310
20	.0396	1.005
22	.0336	.853
24	.0276	.701
26	.0217	.551
28	.0187	.474
30	.0157	.398

Brass Gauge Chart*
Gauge Number	Inches	MM
7	.1443	3.665
8	.1285	3.264
9	.1144	2.906
10	.1019	2.588
11	.09074	2.305
12	.08081	2.053
14	.06408	1.628
16	.05082	1.291
18	.04030	1.024
20	.03196	.812
22	.02535	.644
24	.02010	.511
26	.01594	.405
28	.01264	.321
30	.01003	.255

Copper Gauge Chart*
Gauge Number	Inches	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	.889
22	.028	.711
24	.022	.559
26	.018	.457
28	.014	.356
30	.012	.305

Conclusion

The gauge system has a long history in the metal fabrication industry, starting in the British wire industry to measure wire diameter. Over time, it evolved to include sheet metal thickness.

Today, the gauge system remains widely used alongside standard and metric measurements. It offers a simple and accepted way to indicate sheet metal thickness, ensuring clear communication within the industry.

Although gauge values don’t directly match standard or metric measurements, conversion charts help determine the actual thickness in inches or millimeters. This ensures precise and consistent measurements across different gauges.

The gauge system’s historical roots, broad acceptance, and practical application make it a valuable tool in metal fabrication. It aids professionals in manufacturing, construction, and metalworking, enabling clear communication and accurate measurements for successful projects.

FAQ

Which is thicker 18 or 20 gauge sheet metal?

Contrary to intuitive logic, a higher gauge number corresponds to thinner metal, while a lower gauge number indicates thicker metal. For instance, 18-gauge steel is thicker than 20-gauge steel.

What is gauge size in sheet metal?

The gauge number determines the thickness of sheet metal in inches or millimeters. The higher the number, the thinner the sheet metal. For example, 10-gauges are thicker than 20-gauges.

Which is thicker 14 or 16 gauge metal?

14 gauge metal is thicker than 16 gauge metal. 14 gauge measures 0.083 inches thick, whereas 16 gauge is 0.065 inches thick, making 14 gauge nearly 30% thicker.