Sheet Metal Gauge Converter

This page is the thickness lookup: pick a metal and a gauge, or read all four metals off the table below. If you also need to know what the sheet will weigh, the sheet metal gauge, thickness and weight page takes a sheet size and works it out from the density of the metal. Both pages use the same gauge tables.

Understanding Sheet Metal Gauge

Sheet metal gauge is a numbering system used to indicate the thickness of metal sheets. The system originated in the wire industry in the 1800s and has been adopted for sheet metal. Counterintuitively, a higher gauge number means a thinner sheet. For example, 10-gauge steel is much thicker than 22-gauge steel. This is because the gauge number originally referred to how many times the metal was drawn through a reducing die.

Important: Gauge thickness varies by metal type. A 16-gauge steel sheet is NOT the same thickness as 16-gauge aluminum. Always use the correct gauge table for your specific metal.

All four gauge systems, side by side (thickness in inches):

Read across the 16-gauge row and the point of this page is made in one line: four metals, one number, four different thicknesses, spanning 0.0508 to 0.0635 inches. That is a 25% spread.

Aluminum (Brown and Sharpe / AWG): aluminium borrows the wire gauge system, so 16-gauge aluminium is 0.0508 inches (1.290 mm) against 0.0598 inches (1.519 mm) for 16-gauge steel. It is the thinnest of the four at every gauge, which catches people who swap material without rechecking the number.

Stainless steel: stainless runs on its own gauge table, and it is not the steel one. The numbers are unusually tidy because several land on clean fractions: 16 gauge is exactly 1/16 inch, 11 gauge is exactly 1/8, and 7 gauge is exactly 3/16. Stainless is thicker than plain steel at the same gauge from 20 up, and slightly thinner at 14.

Galvanized steel: this one is routinely explained backwards. A galvanized gauge number refers to the finished, coated sheet, and the zinc adds about 0.0037 inches on top of a base steel sheet of the same gauge. So the steel under 16-gauge galvanized is a normal 16-gauge 0.0598, and the sheet you actually hold is 0.0635. Galvanized is not thinner than plain steel of the same gauge; it is that much thicker.

Practical Tips:

• HVAC ductwork typically uses 22-26 gauge galvanized steel
• Car body panels are usually 18-20 gauge steel
• Roofing panels are commonly 24-26 gauge
• Heavy structural work uses 7-11 gauge
• When ordering from suppliers, always specify the metal type alongside the gauge number to avoid costly errors