How to Measure Earring Gauge | Post Thickness Basics

Measure the straight post of an earring with calipers in millimeters, then match that reading to a gauge conversion chart.

Getting earring gauge right matters for one practical reason: the jewelry has to fit the piercing. A 16g post will not sit comfortably in a hole stretched to 12g, and forcing it can damage the tissue. The good news is that measuring gauge takes about thirty seconds with the right tool and a clear rule in mind.

The core principle is counterintuitive if you’re new to it: the higher the gauge number, the thinner the post. A 20g earring is thinner than a 14g one, and a 0g is far thicker. Keeping that single rule in your head prevents most of the confusion people hit the first time they measure.

What You Need To Measure Earring Gauge

A digital or vernier caliper is the reliable tool for this job. These are inexpensive, readily available, and much more accurate than guessing from a photo or comparing posts side by side.

• Open the caliper jaws wide enough to fit the post.
• Gently place the post between the jaws and close them until they just touch the jewelry.
• Read the millimeter value shown on the display or scale.
• Do not clamp hard — firm pressure can scratch the finish or give you a distorted reading.

If you don’t own calipers, an alternative is comparing the earring against a known-size piece you already own. If a 16g earring fits your piercing comfortably, you can reasonably assume another post of the same visual thickness is also 16g. This method is less precise but useful when the exact number only needs to be “close enough” to order a replacement.

Gauge Conversion Chart: Millimeters To Gauge

Once you have the millimeter measurement, matching it to a gauge number is straightforward with a conversion chart. Below are the most common ear-piercing sizes you’ll encounter.

So a caliper reading of 1.2 mm corresponds to 16g, and a reading of 8.0 mm corresponds to 0g. If you’re working toward that larger size, check out our roundup of the best 0 gauge earrings for stretched lobes when you’re ready to buy.

Common Mistakes And What To Measure Instead

The most frequent error is measuring the wrong part of the earring. The gauge refers only to the thickness of the straight post that goes through your ear — not the decorative front, not the butterfly backing, and not the threaded section where an end screws on. All of those features are shaped differently and will give you a misleading number.

Another trap is forgetting the direction of the scale. People assume a bigger number means a bigger post, which is backwards in gauge sizing. A 12g post is noticeably thicker than an 18g post, even though 12 is a smaller number. The chart above should be your single source of truth when converting.

Third, published charts vary slightly depending on the source, especially near 10g, 8g, and 00g. Don’t panic if one source lists 8g as 3.0 mm and another says 3.2 mm — this is normal rounding, not a mistake on your part. For additional detail on the measuring technique itself, WikiHow’s guide to measuring a gauge piercing walks through the process with clear visuals.

Safety: Matching Jewelry To Your Piercing

The jewelry gauge must match the piercing gauge to fit properly and stay comfortable. If you’re stretching, the rule is to go gradually — moving up a single size at a time rather than forcing in larger jewelry. Rushing a stretch can tear the lobe and set your progress back by months. If you’re buying new jewelry for an existing piercing, measure the piece you already wear and order that same gauge. For detailed instructions, refer to the trusted source on measuring technique, and when in doubt, a professional piercer can identify your gauge in seconds.