Sheet Metal Gauge Chart: A Comprehensive Guide

Precision and accuracy are paramount in metalworking. Whether fabricating automotive parts, constructing industrial machinery, or crafting delicate art pieces, understanding the nuances of sheet metal gauge is essential. Sheet metal gauge serves as a universal language, guiding engineers, artisans, and manufacturers in selecting the appropriate thickness for their projects.

What Do Sheet Metal Gauges Mean? 

Sheet metal gauge refers to a standardized method used to measure and categorize the thickness of sheet metal. This system, which has its roots in the British iron wire industry in the 19th century, provides a series of numerical gauge values to represent different thicknesses. Interestingly, as the gauge number increases, the material thickness decreases for most metals, a counterintuitive aspect that often surprises newcomers.

Gauge charts are crucial because they guide the selection process, ensuring that the material chosen meets a project’s structural and aesthetic needs. Whether you’re constructing a robust architectural framework or crafting delicate jewelry, understanding gauge numbers can significantly impact the outcome of your work.

Importance of Understanding Metal Sheet Gauge

Understanding sheet metal gauge, or thickness, is crucial before purchasing. Here’s why:

Durability

The gauge of metal significantly influences the durability of your project or design. Thicker metal can withstand more wear and tear, making it essential for longevity and resilience applications.

Cost Efficiency

Choosing the right thickness is also a matter of cost. Opting for metal that’s too thick for your needs can unnecessarily increase your expenses, affecting production and shipping costs. Conversely, using metal that is too thin might reduce initial costs but could lead to higher expenses due to repairs or replacements.

Structural Integrity

The integrity of any structure or item made from metal heavily depends on choosing the appropriate thickness. Metal that’s too thin may not support the intended load, leading to structural failures or bending under pressure. Ensuring you have the right gauge for your application is pivotal to avoiding such issues.

How Do Sheet Metal Gauges Work?

Unlike standard or metric measurements, which rely on units like inches or millimeters, gauging follows its own set of rules. To find out the actual thickness of sheet metal, you can refer to a gauge conversion chart. This chart helps translate gauge numbers, such as 18 gauge, into familiar measurements—0.0478 inches or 1.214 millimeters for steel, for example. However, the gauge number, like “18” in this case, doesn’t directly relate to the actual thickness measurements.

It’s important to note that various gauge systems are in use today and differ based on the type of metal. For instance, while 18 gauge steel is 0.0478 inches thick according to one system, 18 gauge aluminum might be slightly thinner at 0.0403 inches. This difference underscores the importance of using a gauge chart to accurately determine the necessary thickness for your metal, ensuring that it meets the specific requirements of your project.

Sheet Metal Gauge Charts

Mild Steel Gauge Chart

Gauge NumberInchesMillimeters
70.17934.554
80.16444.175
90.14953.797
100.13453.416
110.11963.038
120.10462.656
140.07471.897
160.05981.518
180.04781.214
200.03590.911
220.02990.759
240.02390.607
260.01790.454
280.01490.378

Aluminum Gauge Chart

Gauge NumberInchesMillimeters
70.14433.665
80.12853.264
90.11442.906
100.10192.588
110.090742.305
120.080812.053
140.064081.628
160.050821.291
180.040301.024
200.031960.812
220.025350.644
240.020100.511
260.015940.405
280.012640.321
300.010030.255

Stainless Steel Gauge Chart

Stainless Steel
Gauge Number
InchesMillimeters
80.171874.365
90.156253.968
100.140623.571
110.1253.175
120.109372.778
140.078121.984
160.06251.587
180.051.27
200.03750.9525
220.031250.7937
240.0250.635
260.018750.476
280.015620.396
300.01250.3175

Galvanized Steel Gauge Chart

Galvanized Steel
Gauge Number
InchesMillimeters
80.16814.269
90.15323.891
100.13823.510
110.12333.1318
120.10842.753
140.07851.9939
160.06351.6129
180.05161.310
200.03961.005
220.03360.853
240.02760.701
260.02170.551
280.01870.474
300.01570.398

Brass Gauge Chart

Brass Gauge
Number
InchesMillimeters
70.14433.665
80.12853.264
90.11442.906
100.10192.588
110.090742.305
120.080812.053
140.064081.628
160.050821.291
180.040301.024
200.031960.812
220.025350.644
240.020100.511
260.015940.405
280.012640.321
300.010030.255

Copper Gauge Chart

Copper Gauge
Number
InchesMillimeters
70.1804.572
80.1654.191
90.1483.759
100.1343.404
110.1203.048
120.1092.769
140.0832.108
160.0651.651
180.0491.245
200.0350.889
220.0280.711
240.0220.559
260.0180.457
280.0140.356
300.0120.305


Where Did Sheet Metal Gauges Originate?

The history of sheet metal gauges can be traced back to the wire drawing industry before the industrial revolution. Initially, wire was sold by weight, which led to inconsistencies as wires of varying thicknesses could have the same weight. To address this issue, wire drawers began quoting wire based on the number of draws required to create it, with the number of draws becoming the gauge.

This measurement method evolved from drawing wires through progressively thinner dies, assigning each size a numerical gauge. When steelmakers began rolling sheets of steel, they adopted a similar approach. Since measuring sheet thickness directly was challenging, they used the gauge system to specify sheet metal thickness by weight per square foot.

Unlock Precision and Quality: Explore FastMetals’ Sheet Metal Selection Today

The sheet metal gauge chart is more than just a list of numbers; it’s the foundation for successful projects. By understanding and utilizing these charts you can ensure precision and quality in their work. Remember, whether you’re in a professional machine shop or your garage, the key to achieving excellence lies in the details.

For those looking to purchase quality materials, FastMetals offers a wide range of sheet metals suitable for various projects and the expertise to help you select the right gauge for your needs.