So you’re shopping for body jewelry and you see the phrase “8 gauge.” What does that mean? Most of us who are pierced know what gauge size is, but that doesn’t mean everyone else knows, and for those who only have one or two piercings or don’t have a lot of professional modification artists in their area, you might just need a refresher too. So let’s go about this the easy way and have ourselves a little fun.
Here are the basic gauge sizes from smallest to largest, along with their measurements in millimeters and inches. If it looks a little backwards, don’t worry; in body jewelry sizing, the bigger numbers actually mean an item is smaller
20 gauge .8mm 1/32″
18 gauge 1mm .0394″ (about 1/25″)
16 gauge 1.2mm 3/64″
14 gauge 1.6mm 1/16″
12 gauge 2mm .0787″ (about 1/13″)
10 gauge 2.4mm 3/32″
8 gauge 3.2mm 1/8″
6 gauge 4mm .1575″ (about 1/6″)
4 gauge 5mm .1969″ (about 1/5″)
2 gauge 6mm .2362″ (about 1/4″)
0 gauge 8mm .3150″ (about 1/3″)
00 gauge 10mm .3937″ (about 3/8″)
Once standard gauge sizes cut off, anything larger (half inch and above) is normally sized in millimeters or inches. Large gauge plugs and tunnels for instance will be sized as follows:
1/2″ (12mm), 13mm, 9/16″ (14mm), 5/8″ (15mm), 11/16″ (17mm), 18mm, 3/4″ (19mm), 13/16″ (20mm), 7/8″ (22mm), 24mm, 1″. 
When ordering body jewelry, the correct gauge size is needed for a proper fit. If you’re unsure of the correct gauge for one of your piercings, your piercer can tell you or help you to properly measure your current jewelry in order to find out for sure. So basically that really is all there is to it. Now we can get back to the best part: shopping!
