What are Steel Gauge Measurements?

February 20, 2023 | Categorised in:

worker measuring thickness of steel sheet

If you’ve looked for metal sheets before, you may have noticed that their thickness often isn’t measured in familiar metrics like inches or millimeters. While this can seem confusing and needlessly complicated at first, the gauge system is actually an easy way to ensure you get consistent products, no matter where you get them from.

What are gauges?

Gauges (sometimes spelled “gages” and abbreviated “GA”) are a standardized method of measuring and categorizing thin steel products such as sheets, coils, tubes, and wiring. As the gauge number increases, the material thickness decreases in an inverse relationship. For example, 14 gauge steel is thicker than 16 gauge steel. Sheet steel gauges run from 3GA (the thickest) to 38GA (the thinnest).

Where does the measurement come from?

The measurement and its name originate from the industrial revolution and the British iron wire industry, which had no universal unit to measure thickness at the time. The workers drawing the metal wires would quote diameter based on the number of draws performed, which became the gauge (hence why a higher gauge results in thinner material). As more draws were performed, the wire got thinner, and this inverse relationship stuck, even when it comes to sheets and other non-wire products.

Why are they used instead of inches or millimeters?

As mentioned above, the gauge was created to act as a universal or standard unit of thickness. Since then, this system of classification has stuck (and even expanded to products like needles) as an easy way to identify standard sizes of products such as wiring diameter, sheet thickness, and tube wall thickness. So, instead of saying that you need steel sheets that are 0.0478 inches thick, you can simply request 18GA sheets.

Picking the right gauge

The ideal gauge for your steel greatly depends on the application, so there are some key factors to keep in mind. Thicker steel will of course provide more strength, but also has decreased flexibility and a wider bend radius. For example, a fabricator or supplier might recommend switching from 14GA to 16GA sheet — to tighten a bend radius or save weight. Rigid, edged objects can use thicker (or lower gauge) steel, while more flexible or curved objects will likely need thinner (or higher gauge) steel to accommodate this.

A more specific use case is that steel cabinets for storing flammable liquids or materials require all steel used to be at least 18GA steel or thicker (so 18 gauge or less).

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Steel sheet gauge charts

Reading gauge charts is very easy, all you need to do is find the thickness in inches in the table and look at the associated gauge number. While gauges technically have a wider range than this, we’re going to be focusing on a more focused set that’s more applicable to most projects. At Service Steel, we supply premium carbon steel products such as beams, channels, tubing, sheets, and more. Here’s the gauge chart for carbon steel:

Gauge Number

Thickness (in)



























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Whether you’re looking for sheet metal, tubing, or other structural steel products, Service Steel can help you find exactly what your project requires. Even better, our huge inventory of steel is ready to ship so you get it quickly and on time. Not sure what you need? Call our team of experts for help and guidance. If you’re ready to get started, request a free quote online today!