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Gauge describes the thickness of the part that passes through a piercing. Among 20g, 18g and 16g, 20g is the thinnest and 16g is the thickest. For a replacement, match a size you already know is suitable; do not choose a thicker post because its gauge number looks smaller.
Start here
Gauge is easy to confuse with two other numbers: the length of a stud post and the diameter of a hoop. A listing can give all three, but they answer different questions.
Read the number and the unit together
Maria Tash's sizing guide explains that higher gauge numbers mean thinner jewelry. Millimeter equivalents can be rounded differently between listings, so keep both the maker's gauge and millimeter measurement in your notes.
| Marking | Approximate thickness | What it does not tell you |
|---|---|---|
| 20g | 0.8 mm | The length of the post |
| 18g | About 1.0 mm | Whether its front fits another brand's post |
| 16g | About 1.2–1.3 mm in retail size labels | The space inside a hoop |
These are shopping references, not a fitting prescription. Cords Club lists a 0.8 mm post on Essential Hoops and a 1 mm post on its Postage Stamp stud. Maria Tash's Plain Gold Hoop listing labels its 16g option 1.3 mm.
A similar-looking earring can have a different gauge
Imagine that a small hoop and a flat-back stud look equally delicate from the front. Their visible decoration does not establish that the wearable posts have the same thickness. Compare the specification line, not the overall size in a model photograph.
Also distinguish the decorative end's connection pin from the wearable post. Measuring a tiny pin that goes inside a hollow post will not tell you the thickness of the part that passes through your ear. Keep those dimensions separate when asking about replacements.
How to find your existing size
Start with your order confirmation, the original product page or a fitting record from your piercer. Save the exact model and variant beside the size. If you bought several earrings together, confirm which item the measurement belongs to.
If that trail is missing, take the jewelry to a qualified piercer for identification. A photograph next to a ruler is often more useful for identifying a design than for resolving a tiny difference in post thickness. There is no need to order several gauges as a trial-and-error fitting kit.
Can you switch between gauges?
Do not treat the conversion table as instructions to force a different size into a piercing. The APP emphasizes that appropriate gauge and dimensions depend on the piercing and anatomy. Ask a piercer about an uncertain change, particularly for a new or healing piercing.
For a straightforward replacement, write a short specification: maker, model, closure, gauge and post length. That turns “I need a small earring back” into a useful request. Our online earring buying guide covers the remaining material and quantity checks before checkout.
Sources 5
Explore Cords Club
Use the model’s gauge alongside a known suitable size before choosing a Cords Club design. A different decoration is not a reason to change gauge.
Shop Cords Club ↗Affiliate linkSources
This guide draws on published product information, not hands-on testing. Sources and check dates are listed below.
- Maria Tash: Jewelry Size GuideSource checked Sep 23, 2026
- Cords Club: Essential Hoops specifications and careSource checked Sep 23, 2026
- Cords Club: Postage Stamp Flat Back Stud specificationsSource checked Sep 23, 2026
- Maria Tash: Plain Gold Hoop gauge optionsSource checked Sep 23, 2026
- Association of Professional Piercers: Jewelry for Initial PiercingsSource checked Sep 23, 2026
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