Metals are measured in varying units. This seemingly strange set of measurements is in part due to history of each metal.
The steels (and stainless steels) are measured in gauge, and correspond with a decimal inch thickness. The higher the gauge number, the thinner the sheet. 16ga (gauge) is roughly 1/16 inch, which is a nice thing to remember if you remember nothing else about sheet metal gauge.
Galvanized steel, which has a thin layer of zinc on steel sheet, also uses the gauge system. Because of its thin coating, it slightly thicker when converted into inches than uncoated steels.
Aluminum is measured by the more familiar decimal relationship. Copper is another story altogether. Copper is measured in ounces per square foot, which continues to this day in part due to copper’s use in computer transistors, the smallest of measurements. 1oz copper is equal to 1.37 mils, or thousands of an inch. For architectural use, 48oz copper is close to 16 ga stainless steel, to put things in perspective.
Mastering the world of architectural metals might seem like traveling across the different countries of Europe. Each material has its own language, and understanding them can take time.https://www.azahner.com/wp-admin/post.php?post=725&action=edit&classic-editor=1#save
The aluminum and copper industries are as different from each other as they are from the steels. Monel, titanium, zinc, for example, address their own industries with a jargon created from a mixture of the others. This leads to confusion for those using the materials. You must translate your understanding from ounces per square foot to decimals or gauge numbers, depending on your familiarity. Below is a simple chart which should help when comparing standard sheet metal thicknesses between various metals.