20 gauge steel thickest steel gauge 12 gauge steel More complete table 24 gauge Dictionary of Units of Measurement Dictionary of Units of Measurement This answers the question, for steel as well as aluminum Sheet Metal Thickness Gauges 10 gauge 11 gauge Dictionary of Units of Measurement 11 gauge This answers the question, for steel as well as aluminum More complete table checking steel gauges galvanized steel 10 gauge steel 10 gauge sheet metal www.unc.edu/~rowlett/units/scales/sheetmetal.html 24 gauge Sheet metal thickness steel Sheet Metal Thickness Gauges: Dictionary of Units of Measurement More complete table 16-gauge 11 gauge