18G vs 20G vs 16G Earrings — Which Gauge Actually Fits?

You order a pair of flat-back earrings online. They arrive, you go to put them in, and the post won't pass through. Or it goes in easily — too easily — and the decorative front won't sit straight.

Neither of those is a defect. It's a gauge mismatch, and almost nobody explains it before you buy.

The three numbers, in millimetres

Gauge measures the thickness of the post — the bar that passes through your piercing. In body jewelry it's written with a G:

20G = 0.8mm
18G = 1.0mm
16G = 1.2mm

The higher the number, the thinner the post. That runs backwards from almost every other measurement you deal with, and it's the single most common source of confusion.

The reason is historical: the scale comes from wire manufacturing, where the number counted how many times a rod was pulled through a drawing die to make it thinner. More passes, thinner wire, higher number. The convention outlived the process.

The practical version: 20G is the thinnest of the three. 16G is the thickest. The difference between them is 0.4mm.

What gauge is your piercing?

Here's the honest answer: you probably can't tell by looking, and neither can we.

What you can do is narrow it down by how you were pierced.

Pierced with a gun — at a mall kiosk, a pharmacy, a jewelry counter — and your lobes are most likely 20G. Gun studs are made thin because the stud itself is forced through the tissue, and a thinner post meets less resistance.

Pierced at a professional studio with a hollow needle, and you're more likely 18G or 16G. Piercers generally prefer a slightly thicker gauge: it's more stable in the channel, less prone to migration, and heals more predictably.

That's a tendency, not a rule. Studios vary, decades pass, and piercings change. If it matters to you — and if you've had trouble with earrings fitting, it does — the fastest way to find out is to take a pair you own into a studio and ask. Most piercers will measure it in under a minute and won't charge you.

Down is easy. Up is not.

This is the part that actually determines whether a pair will work for you.

Going thinner works. A 20G post is narrower than the channel left by an 18G or 16G piercing, so it passes through. It fits — but it doesn't fill the channel. There's room to move, which means the earring can rotate or shift, and a decorative front may not stay square against your lobe. Some people never notice. Some find it maddening.

There's a slower effect too: a piercing that consistently holds thinner jewelry may gradually become accustomed to that smaller size.

Going thicker doesn't. A 16G post will not pass through a 20G piercing. Forcing it tears tissue. Moving up a gauge is a stretching process, done gradually and properly, and it's not something to attempt because a pair of earrings you liked came in the wrong size.

So: measure the smallest piercing you want to wear the earring in, and buy at or below that gauge.

The thing gauge doesn't tell you

It's tempting to read all of the above and conclude that thinner is better — that 20G is the comfortable choice.

It isn't. A 20G post in an 18G piercing is thin and loose. A 20G post on a butterfly back still digs into a pillow. A 20G post in the wrong metal still reacts against sensitive skin. A 20G post that's too long still leaves the back sitting proud of the earlobe.

Gauge tells you how thick the post is. It doesn't tell you how comfortable the earring will be.

Comfort isn't a number. It's what happens when five things line up at once:

Post gauge — thick enough to sit stable in the channel, thin enough to pass through it. This is the compatibility check, and it comes first because nothing else matters if the earring won't go in.

Back design — a flat disc sits flush behind the lobe; a butterfly clutch protrudes and becomes a pressure point the moment your ear meets a pillow. This is the difference between flat-back and butterfly-back, and for anyone who sleeps in their earrings it outweighs gauge entirely.

Post length — the distance between the flat back and the decorative front. Too long and the back stands off your skin, reintroducing the exact gap you were trying to eliminate. Our 5mm vs 6mm vs 8mm guide covers how to pick this, and it's the number that surprises people most.

Material — an earring you never take out is in contact with your skin permanently, through sweat, showers, and sleep. What it's made of stops being a detail. ASTM F136 implant-grade titanium is the specification worth knowing, and it's a stricter claim than "hypoallergenic" or "medical grade," both of which mean whatever the seller wants them to mean.

Construction — how the piece assembles and whether anything on it can catch. A threadless push-pin has no screw threads to snag on hair or fabric. Here's how the mechanism works, and here's how threadless differs from threaded.

Change any one of those and the earring changes. Gauge is one input out of five, and it's the one that gets quoted most often precisely because it's the easiest to put on a product page.

Why TISTELLA uses 20G

Every TISTELLA post is 0.8mm — 20G — across the whole line, flat-backs and hoops alike.

The reason is fit, not comfort. 20G is widely used for standard lobe earrings, particularly in conventional pierced-ear jewelry, and a 20G post is also narrow enough to pass through piercings made at 18G or 16G. Choosing it means the largest possible number of people can wear the earring at all. Choosing 18G would fit fewer people, and choosing 16G would fit fewer still.

What makes our earrings comfortable to wear is the rest of the system: a 3mm flat disc with nothing to press into a pillow, a hollow post with a smooth 0.45mm pin and no threads anywhere on the piece, implant-grade titanium throughout — including the pin, because steel can't be welded to titanium — and two post lengths instead of one. The Air⁵ series uses a custom 5mm post for thinner lobes, because the 6mm industry standard leaves the back sitting proud on a lot of people. Everything else uses the 6mm standard.

The 20G post is what gets it through the door. The other four things are what make you forget it's there.

Where this leaves you

If your piercing is 20G, our posts fill the channel the way they're meant to. Anything in the line works.

If your piercing is 18G or 16G, our posts pass through without difficulty but sit loose in a wider channel, which means the earring can rotate. Whether that's a problem depends entirely on the design.

Designs that rotate without showing it. A shape with no top or bottom looks identical at every angle. Solo is a single round CZ; Stellara is a symmetrical star. Spin either one and nothing changes.

Designs that right themselves. When the post attaches at the top of the piece and the weight sits below it, gravity does the work — the same reason a pendant on a chain always hangs straight. Icicle is a kite cut with the wide end at the top and the point below it. Prism Drop and Cascade hang from a single point by design. These sit level in a loose channel because they aren't relying on friction to stay level.

Designs that need a snug fit. Horizontal and winged shapes carry their weight evenly on both sides of the post, so there's nothing pulling them back to level. In a 20G piercing they sit exactly where you place them. In a wider one, they may drift. If you're 18G or 16G and you want one of these, buy at your own gauge instead — we'd rather tell you now than have you find out after it arrives.

If you don't know your gauge, ask a piercer before you buy anything, from us or anyone else. It's the one measurement that decides whether a pair is even an option, and it takes a minute to settle.

For everything else about how these earrings work — sizing, materials, wear, and care — start with the complete guide to flat-back earrings.