GAUGE = Standard measurements for bar thickness.
0.8mm = 20G = Standard size for thin nose bars and rings.
1mm = 18G = Standard size for nose bars and rings.
1.2mm = 16G = Standard size for cartilage bars and rings. septum jewellery, daith, eyebrow and rook jewellery.
1.6mm = 14G = Standard size for belly bars, nipple bars and rings, tongue bars
2mm = 12G
3.2mm = 8G
4mm = 6G
5mm = 4G
6mm = 2G
7mm = 1G
8mm = 0G
10mm = 00G
12mm = 1/2"
14mm = 9/16"
16mm = 5/8"
19mm = 3/4"
22mm = 7/8"
25mm = 1"
Length measurements provided on listings are the distance between ends or sides and does not include the ends or the ring sides.
The images below show where to measure gauge and length on common jewellery styles.