TONGUE JEWELRY SIZING INFORMATION: Straight barbells in 14 gauge 5/8 inch (16mm) length is the most common tongue piercing size. Initial tongue piercings are usually done with a 14 gauge, 7/8 inch (22mm) straight barbell to compensate for the swelling of the tongue after piercing. When the tongue heals, most people can use a 5/8 (16mm) length or shorter, but not everyone! Again, this is a guideline.