What are 3.5, 4.5, etc, gauge?

Question

Hi all,

recently I've been coming across references to 3.5 gauge, 4.5 gauge and so on, but I cannot find how thick that is (in inches or mm) for rod and wire.

Please could anyone tell me the fractional gauges, or point me to a on-line reference to them? I would really appreciate any help.

Answer 1

Definition 1

Unit of thickness of a metal sheet or wire. (1) For sheet metal, a retrogressive scale (higher numbers mean lower thickness) that starts with 10 gauge representing a thickness of 3.416 millimeters or 0.1345 inches. As the gauge number increases, the thickness drops by 10 percent. For example, a 12 gauge sheet is 2.732 millimeters thick, and a 13 gauge sheet is 2.391 millimeters thick. (2) For wire thickness there are two scales, see American wire Gauge for the first one. The second is a metric scale in which a gauge number is equal to 10 times the diameter of the wire in millimeters. For example, a 5 gauge wire is 0.5 millimeter in diameter and a 6 gauge wire is 0.6 millimeter in diameter. Also spelled as gage.