Standard 20 gauge steel is .0359 inches thick. Galvanized 20 gauge steel is thicker at .0396 inches and 20 gauge aluminum is thinner at .0320 inches thick. The thickness of a piece of steel is also indicative of its maximum bending capacity.
The higher the gauge of a piece of sheet metal, the lower its thickness. This means that 3-gauge metal is thicker than 20-gauge metal.
Sheet metal is used for a variety of purposes, one of which is brakes on a vehicle. Sheet metal may also be used in construction, such as on the roof of a building. There are also instances of using sheet metal in interior design; it can be used to cover floors or walls.