Flat back earrings: what they are, the right size, and why piercers use them

A flat back earring is a straight post with a smooth, flat disc on the back and a decorative end on the front. The disc sits flush against your skin, and the end is either pushed into the post or screwed into it. That is the whole design, and it is the reason professional piercers use it for almost everything.

If you have been pierced in a studio in the last decade, you were almost certainly given one. If you have been searching for why your studio jewelry has no butterfly clasp, this is why.

Two names for one thing

In a studio it is a labret stud, because the design was first used for lip piercings, where a flat disc inside the mouth was the only comfortable option. When the same jewelry became the standard for ears, the mainstream name flat back caught on.

They are the same object. A shop selling “labret studs” and a shop selling “flat back earrings” are selling the same thing, and the sizing below applies to both.

Why piercers stopped using butterfly backs

A traditional stud earring has a post and a butterfly clasp that grips it. That design has four problems for a piercing that is healing, and two that persist forever.

The clasp digs in. A butterfly has edges and a spring. Sleep on it and it presses into the skin behind your ear. A flat disc has nothing to press with.

It traps debris. The folds of a butterfly collect skin, dried discharge and product, and sit against the wound. A disc wipes clean.

The post cannot be sized. Stud earrings come in one length. A flat back comes in every length from 5 to 12 mm, so the post can match your tissue exactly, with room for swelling at the start and none once it has gone.

The end can be changed without removing the post. With a flat back, the decorative front comes off and the post stays in the piercing. Swapping a butterfly stud means taking the whole thing out and threading it back through a channel that would rather you did not.

The two permanent advantages are comfort and headphones. A correctly sized flat back sits flush on both sides, so nothing catches on a pillow or presses under an over-ear cup. That is why people with fully healed lobes convert to them and never go back.

The three parts, and what each measurement means

The post. Measured in two ways: gauge (thickness) and length. Gauge runs backwards, so a smaller number is thicker. Length is the wearable section between the disc and the end.

The disc. The flat back itself, usually 3 to 5 mm across. Larger discs spread pressure and are used in the mouth; smaller ones are neater behind an ear or inside a nostril.

The end. The decorative front, which either has a thin pin that pushes into the post (threadless) or a small screw thread that turns into it (internally threaded). Both keep the outside of the post smooth, which matters more than most people realise. The threading guide explains why, and why externally threaded jewelry should never go through a healing piercing.

Sizes by placement

These are the usual ranges. Your own anatomy can sit outside them, and the right answer for a healing piercing is whatever your piercer measured.

The downsize is not a style choice. A post left at its initial length after swelling goes down moves in the channel and catches on everything, and that movement is the single most common cause of irritation bumps. Downsize at four to six weeks for a lobe, six to ten for cartilage, two to four for a lip. See when to change your jewelry.

Working out what size you have

Take the end off, and measure the post from the disc to the tip with a ruler marked in millimetres. That is your length. Gauge is harder to eyeball; if your piercer did not tell you, the gauge chart converts the common thicknesses, and a studio will measure it in seconds.

Do not buy by “small, medium, large.” A seller who cannot give you gauge and length in millimetres is not selling body jewelry.

Changing the end

Threadless: bend the pin very slightly, about ten degrees, push it into the post, and twist gently as it seats. Tug lightly to check. If it falls out, bend a fraction more; if it will not go in, straighten a fraction.

Internally threaded: line the end up square and screw it in until it stops. Do not force a cross-threaded end.

Both are done from the front while holding the disc steady with a fingertip behind the piercing. Wash your hands, work over a towel rather than a sink, and only do this on a piercing that has finished healing. Changing the front does not disturb the channel the way changing the whole post does, which is another reason the design works.

Material matters as much as the design

A flat back in the wrong metal is a well-shaped piece of the wrong metal. For a healing piercing that means implant-grade titanium, ASTM F136, or solid 14k gold or higher. Plated jewelry sheds its coating into the wound, and “surgical steel” is a label with no standard behind it. The materials guide covers what the standards mean and which to ask for.

What to look for when buying

• Gauge and length in millimetres, not letters.
• Threadless or internally threaded, stated plainly.
• The alloy standard, not just the metal name.
• A polished disc with no visible seam or casting line.
• A brand you can look up, ideally one listed by the Association of Professional Piercers’ jewelry verification programme.

Walk away from anything described as “hypoallergenic” without a standard, anything with a visible screw thread on the outside of the post, and anything sold as a one-size set.

Converting healed lobes

If your lobes were pierced years ago with ordinary studs and you want to sleep on them, a 20 or 18 gauge flat back with a 6 mm post is the usual swap. Have a piercer check the gauge of your existing jewelry first; a lobe pierced with a thin stud may need a moment to accept an 18g post, and forcing it is not the answer.

The rest of the jewelry guides cover materials, threading, sizing and retainers.