Sheet Metal Gauges: The Complete Guide

Before you fabricate sheet metals, it is vital to know the gauge or thickness.

With this information, you can choose the right tool, fabrication technique and component.

Today’s guide takes you through everything you need to know about sheet metal gauges – take a look.

What Is Sheet Metal Gauge?

Sheet metal gauge is a unit of measurement used to describe the thickness of sheet metal. It provides information on the size of a sheet metal product, or how thick its material is.

Usually, the numerical value of sheet metal gauge is calculated by dividing the material thickness by its width. Always remember, the lower the gauge number, the thinner the metal. For example, 16-gauge sheet metal is much thinner than 32-gauge.

Sheet metal gauge has been standardized throughout the world, meaning that it can be used as a reliable measurement across all countries. The most common gauges are 16, 20, 24, 28 and 32.

History Of Sheet Metal Gauge System

The history of the sheet metal gauge system dates back to 1789 and was created by a master gunsmith in France.

This system was a standardized method to measure the thickness of sheets in a specific area based on that area’s function and manufacturing needs. In the US, Henry Harder (originally from Germany) adapted these standards to American manufacturers through the American Society of Mechanical Engineers (ASME).

This American version is still utilized today and is why we still use the imperial decimal equivalent when referring to gauge sizes.

How To Measure Sheet Metal Gauge

How To Measure Sheet Metal Gauge
How To Measure Sheet Metal Gauge

When it comes to measuring sheet metal gauge, there are two main ways: using a tape measure or using a gauge wheel.

A tape measure is more precise than a gauge wheel because its markings are more accurate. Therefore, ensure your sheet metal thickness is accurate with these quick and simple guidelines on how to accurately determine sheet metal gauge. Using a sheet metal gauge chart, it is possible to convert the metal sheet gauge to inches or millimeters.

With just three steps, you can determine if your sheet metal has been over-or under-sized:

Option 1: Measuring Sheet Metal Gauge Using Tape Measure

You will follow three simple procedures in this option, which include:

Step 1

Establish the sheet metal thickness using the millimeter hash marks of your tape measure. Take note that the tape measure features two differing measurements, that is, mm and cm. However, using the “cm” scale will not give the precise measurements that is desired.

Step 2

The number recorded in mm can be converted to inches. Simply multiply the number by 0.03937.

Step 3

Use the gauge chart to compare the result you obtained in inches. From the chart, you will determine the suitable gauge of your metal sheet.

Option 2: Measuring Sheet Metal Gauge Using Gauge Wheel

A gauge wheel refers to a simple tool having no moving parts. The tool can help you measure the thickness of both sheet metal and wire. Measurement of sheet metal gauge using gauge wheel entails 3 simple procedures consisting of:

Step 1

Use the appropriate gauge wheel so as to get the right sheet metal gauge measurements. When measuring nonferrous metals, such as copper, silver, or gold, confirm that the gauge wheel front is labeled “nonferrous.” Similarly, choose the suitable gauge wheel if you are to measure the thickness of ferrous metals, like stainless steel, or cast iron.

Step 2

The gauge wheel has openings of varying sizes around it, with each opening having a number marked on its front. You determine the sheet metal thickness by placing it in every opening till you get one that it precisely fits in. Nevertheless, you should not use the round cutouts beneath the openings. They are not the correct ones to use, rather, you should always use the top openings.

Step 3

After locating the right opening in which your sheet metal fits perfectly in, note the number marked in the front. For instance, in case your metal sheet fits within an opening labeled 18, it implies that you have an 18 gauge sheet metal.

Sheet Metal Gauge

Using Sheet Metal Gauge.

In the sheet metal industry, gauges help is specifying the sheet metal thickness. The gauges are neither metric nor standard in their measurements, so their values are independent of the measurement systems used. When measuring the thickness of sheet metal, you can use a gauge conversion chart to determine its actual thickness millimeters or inches. An 18 gauge steel, for example, is 1.214 millimeters or 0.0478 inch on a gauge conversion chart.

There is no connection between gauge number “18” and the actual measurements. Today, there are a number of different gauge systems that are used, as well as specific gauge designations for different types of metals. Using one gauge system, the thickness of 18 gauge steel is 0.0478 inches, whereas the thickness of 18 gauge aluminum is 0.0403 inches. Due to the thickness variations, you should use a gauge chart to make sure the sheet metal meets the dimensions desired.

Sheet Metal Gauge Chart

To determine the metal gauge you require for your project, you can use the sheet metal gauge chart below.

The chart can help you establish the corresponding sheet metal thickness, in millimeters or inches, for a gauge value from the chosen gauge size standard.

Sheet Metal Gauge Chart

Sheet Metal Gauge Chart

Importance Of Choosing Right Gauge For Sheet Metal Fabrication

Gauge For Sheet Metal

Buying any metal sheet without factoring its thickness is very risky. For this reason, choosing the correct gauge is important during sheet metal fabrication:

  • Economic: You do not have to use thick metals in every design. Hence, you may increase the production and shipping costs of your product if you use too much or too dense metal.
  • Structural distortion and issues: For specific designs, utilizing too thick or  too thin metals may lead to structural deformation and issues within the product.
  • Durability: The gauge of the sheet metal you use will largely determine how long your design will last. There are projects that demand thick metals that have exceptional strength, and there are others that don’t.

This means that the durability of any project relies on the sheet metal gauge.

  • Weldability: Another way that gauge affects sheet metal fabrication is by determining whether or not it can be welded together or not. If you want to fuse two metal pieces together during fabrication, you will need to have similar gauges. This will ensure that the two metal sheets fuse properly when welded together.
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