How to Use the Sheet Metal Gauge Converter
In sheet metal work, thickness is often specified as a gauge number instead of mm or inches. A smaller gauge number means thicker metal, and a larger number means thinner metal. The catch is that steel, stainless steel, and aluminum each use different gauge standards, so the same gauge number does not mean the same thickness. For example, 18 gauge steel is about 1.214mm, while 18 gauge aluminum is thinner at about 1.024mm.
Select your material and gauge number to instantly see the actual thickness in both mm and inches. Useful for reading fabrication drawings, ordering laser cutting or bending work, choosing welding rod diameter, and checking sheet specs for ductwork or hood fabrication.
Steel values use the Manufacturers' Standard Gauge (MSG), and aluminum values use the Brown & Sharpe (B&S) gauge system. Stainless steel is commonly labeled with the same MSG numbers as steel in general practice, though exact thickness can vary slightly between suppliers — for precision orders, always confirm against the actual mill spec sheet.
Frequently Asked Questions
18 gauge steel is about 1.214mm (0.0478in). 18 gauge aluminum is thinner, at about 1.024mm, since steel and aluminum use different gauge standards. Always select the correct material first.
Gauge numbering originated from the rolling process. Lower numbers represent earlier, less-rolled (thicker) sheets, while higher numbers represent sheets rolled thinner.
In practice, stainless steel is often labeled using the same Manufacturers' Standard Gauge (MSG) as steel, though exact thickness can vary slightly by supplier. Check the actual mill spec for precision work.