Many people ask me "Why does the thickness of steel diminish as the gauge increase(ie: 16 gauge steel is thicker than 20 gauge steel). The explanation comes from the original development of a gauge measurement system in which the control measurement was based on 1" thick steel plate. From this base thickness, the steel was measured in diminishing fractions such as 1/14", 1/16", 1/20" and so on. The bottom number of the fraction was adopted as the "gauge" and so 1/16" became 16 gauge, 1/20" became 20 gauge. The concept makes sense but without explanation, the converse number is often confusing. Therefore by taking the gauge number and returning it back to a fractional format, one can discover the actual nominal thickness dimension, in inches, of sheet steel.
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