Sheet Metal Gauge Chart Explained: Metal Thickness, Gauge Numbers, and Conversion Guide

When people talk about sheet metal, they often describe how thick it is using something called a gauge (sometimes spelled gage). To make it easy to understand, check out our Sheet Metal Gauge Chart for a quick reference.

You can think of the gauge number as a special code that represents the thickness of the metal sheet — but it works backwards from what you might expect:

• A small gauge number means the metal is thicker.
• A large gauge number means the metal is thinner.

For example:

• 10-gauge steel sheet is thick and heavy.
• 20-gauge steel sheet is much thinner and lighter.

 The chart below is our best attempt to capture all of the standard gauge thickness of different materials.

Sometimes, the metal goes through extra processing — like polishing (which makes it a bit thinner) or adding protective coatings or plastic films (which can make it slightly thicker). So, the final thickness might not be exactly the same as the standard gauge number.

That’s why it’s important to double-check with your supplier to make sure you know the actual thickness you’ll be getting, especially if the material has been polished or treated in some way.

Sheet Metal Gauge Chart