The diameter or thickness of a wire is described as the gauge. Wire gauges can be a bit confusing as the wire gets thinner as the gauge gets higher (so 18 gauge is thicker than 30 guage!). To add to the confusion there are two types of gauges. On this website we use the more common American Wire Gauge but we also quote the thickness of the wire in millimeters which is becomming more common. Below is a chart that details the different wire gauges and the typical uses of that gauge: