We’ve explored the topic of gauge before. Gauge refers to the thickness of your metal, but contrary to many common units of measure, a higher gauge does not mean a larger or thicker metal. Quite the opposite. As the gauge number goes up, the thickness goes down.
While it is common knowledge that high gauge steel is thinner than low gauge steel, few people know why. But it’s true, 16 gauge steel is thicker than 20 gauge steel, for example.
The explanation comes from the early development of a steel gauge measurement system in which the control measurement was based on a one inch thick steel plate. The one inch thickness of the steel was measured in diminishing fractions such as 1/14”, 1/16”, 1/20” thick and so on. The denominator, the bottom number, of the fraction became an easy and concise identifier of the steels thickness, and eventually craftsmen stopped saying the entire fraction, instead adopting the denominator as the “gauge number.”
Thus, 1/16” became 16 gauge and 1/20” became 20 gauge. This is why 16 gauge steel is thicker than 20 gauge steel. Because 1/16” is thicker than 1/20”.
It is easy to see how one might be confused if they didn’t understand that the gauge number is the denominator of a fraction. Moreover, by taking returning the gauge number to its fractional format, one can discover the actual nominal thickness dimension, in inches, of sheet steel.
And that is why low gauge steel is thicker than high gauge steel, and vice versa.