Gauge is the thickness of the jewelry that passes through your piercing. A smaller gauge number means a thicker piece. The millimeter number beside it may describe something entirely different, such as post length or ring diameter. Read the measurement labels before comparing two products.
A quick gauge conversion chart
| Gauge | Thickness |
|---|---|
| 20G | 0.8mm |
| 18G | 1.0mm |
| 16G | 1.2mm |
| 14G | 1.6mm |
| 12G | 2.0mm |
| 10G | 2.4–2.5mm, depending on listing convention |
| 8G | 3.0–3.2mm, depending on listing convention |
These are common retail equivalents, not a stretching sequence. Use the seller's actual millimeter specification where rounding differs. For a fuller reference, see our existing body jewelry gauge size guide.
Example 1: a 16G, 8mm, 3mm flat back
In a listing that labels these as gauge, post length and gem size, the shaft is approximately 1.2mm thick, the wearable post is 8mm long and the visible gem is 3mm wide. A 2mm gem option changes the appearance. A 6mm post option changes the wearable length. Neither change necessarily changes gauge.
That distinction helps when the front looks right but the backing protrudes: a smaller gem does not solve a post-length question. Keep the three choices separate in your cart.
Example 2: a 16G, 10mm ring
Here, 16G describes thickness and 10mm usually describes the inner diameter—the empty opening across the ring. Confirm that the listing uses inner diameter, especially for shaped jewelry. A 16G, 8mm ring has the same thickness but a smaller opening. A 14G, 10mm ring has a similar opening but a thicker wearable section.
This is why “I wear 8mm jewelry” is incomplete. Eight millimeters could be a ring opening, a stud length or a stretched-lobe wearable diameter.
Is 18G interchangeable with 16G?
No. Moving from 18G to 16G increases thickness; it is not merely another way to label the same size. Do not force a thicker piece into a piercing. A thinner replacement can also change how the piercing is supported, so confirm the appropriate gauge rather than choosing the available option at random.
How to recover an unknown size
- Check the original receipt and the exact variant, not only the product title.
- Keep a comfortable spare in its labeled package.
- Have loose jewelry measured by a piercer if the record is missing.
- Record gauge, wearable length or inner diameter, connection and material together.
Do not estimate gauge from a photo or use a ruler against a piercing. A practical note might read: “16G / 8mm wearable post / threadless / 3mm top,” with the product name alongside it. That note is a shopping record, not permission to reuse the same size in every placement.
Continue reading: 6mm vs. 8mm Flat-Back Posts: Length and Fit.
Feature image: AI-generated editorial illustration, not an exact product photograph or a size reference. Product listings show the actual designs and specifications.
Shop related jewelry at Kruelty
Use your confirmed measurements to compare these specific designs. Check the current product options, materials and package contents; the examples are not a universal size recommendation.
- Titanium Labret Stud 20 18 & 16 Gauge Threadless Ring Clear Gem — Compare the separately listed gauge, 6mm or 8mm post length, and 2mm or 3mm gem options.
- Titanium Belly Ring 14 Gauge Internally Threaded Double Round Opals — A fixed double-opal design to compare with floating or dangling silhouettes.