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.

Short answer: yes — 20G is smaller. 20G is 0.8mm, 18G is 1.0mm, 16G is 1.2mm; the higher the number, the thinner the post. A thinner post passes through a wider piercing, so a 20G earring fits 20G, 18G and 16G piercings — which is why every TISTELLA earring is made on a 20G post. Which designs stay level in a wider hole is the part worth reading on for →

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 almost certainly 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 it could be 20G, 18G or 16G, depending on the piercer and what you were pierced for. Studios vary, and they've varied over the years.

The good news is that this matters far less than it sounds, and the next section is why.

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 straight through — no resistance, no stretching, nothing you have to get right. Thinner always fits wider.

What a thinner post doesn't do is fill the channel completely, so there's a little room for the earring to turn. Whether you'd ever notice depends on the shape of the front, and that's a solvable problem — there's a section on it at the end.

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 the rule only runs one direction: a post at or below your gauge goes in; a post above it does not. At 20G, ours sits at the bottom of the range — an exact match in a 20G piercing, and no trouble in anything wider. See the full 20G line →

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 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 — thin enough to pass through the channel. 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, because it's a number you can look up rather than a word a seller chose.

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.

For hoops specifically, gauge is only one of three measurements that decide fit — the other two are the hoop's inner diameter and the thickness of the wire itself, and they're easy to confuse. We break all three down in hoop earring sizes.

The reason is fit. 20G is the standard for 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 — browse all flat-back earrings.

If your piercing is 18G or 16G, our posts go through without difficulty and sit a little loose in the wider channel, which means the earring can turn. Whether that's visible at all depends on the design — and most of the line is unaffected.

Designs that turn 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 prefer 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 channel they can drift a few degrees — easy enough to nudge back, and if you have more than one piercing, these are the ones to put in your snuggest hole.

If you don't know your gauge — and most people don't — 20G is the one that doesn't require you to find out. It's the narrowest of the three, so it goes into whatever you already have. If you ever want the number for its own sake, any piercer will measure a pair you own in under a minute, usually for nothing.

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