After size 00 ear gauges are expressed as fractions of an inch, or whole inches, such as one-half, three-quarters and one inch. Typically, gauges past 00 are plugs for stretching existing piercings.
Earrings and piercing tools measure in gauge sizes that correspond to actual measurements; gauge sizes are always even numbers. Most earlobe piercings use size 18 or 20 needles and jewelry. A 20-gauge piercing is approximately 0.03 inch and an 18-gauge is 0.04 inch. For cartilage piercings, such as the helix or tragus, a 16-gauge, or 0.05-inch, piercing is common. An industrial piercing, a long barbell stretching through two holes across the top of the ear cartilage, is most commonly a 14-gauge, or 0.06-inch, piercing. Most often, the intent of jewelry beyond 14- or 12-gauge is to stretch an existing earlobe piercing through the insertion of gradually larger pieces of jewelry. The final gauge size is usually 00, or 0.375 inch, after which jewelry goes by size in inches.
Stretching is a way to accommodate larger pieces of jewelry without starting with a large hole that could damage tissue and prevent downsizing in the future. Stretching is a slow process and each new stressing must heal before a new one begins; healing times vary from weeks to months, and stretching too quickly causes scar tissue. With proper care and attention, people achieve stretchings up to a full inch or more.