Measuring a septum ring correctly comes down to two numbers: the gauge (thickness of the jewelry bar) and the diameter (the distance across the inside of the ring). You can measure both at home with a caliper or a ruler, and the process takes less than a minute once you know what to look for. Gauge is measured in millimeters and uses a standard sizing scale, while diameter is simply the inner width of the circle measured edge to edge.
What Do Gauge and Diameter Actually Mean?
Gauge refers to the thickness of the metal bar that passes through your piercing. In the United States, septum jewelry is sized using the American Wire Gauge (AWG) system, where smaller numbers mean thicker metal. A 16 gauge ring is thicker than an 18 gauge ring, even though 16 is a smaller number.
Diameter is the distance across the inside of the ring, measured from one inner edge to the opposite inner edge. This determines how far the ring extends below your septum and how much room it leaves for your anatomy. Diameter is measured in millimeters.
Both numbers matter. A ring with the correct gauge but wrong diameter will feel uncomfortable or sit poorly. A ring with the correct diameter but wrong gauge may not fit through the piercing hole at all.
How To Measure Septum Ring Gauge And Diameter With a Caliper
A digital caliper is the most accurate tool for measuring jewelry you already own. You can buy one for about $15 at hardware stores or online. If you wear septum rings regularly, it is worth the investment.
To measure gauge, place the caliper jaws around the thickest part of the ring’s bar. Do not measure the decorative ends or balls — only the straight metal section that passes through your piercing. Close the jaws gently until they touch the metal, then read the measurement in millimeters.
To measure diameter, open the caliper jaws and place them inside the ring. Measure from the inner edge on one side to the inner edge on the opposite side. This gives you the internal diameter, which is the number used in jewelry sizing.
If your caliper reads in inches, multiply the inch measurement by 25.4 to get millimeters. Most digital calipers have a button to switch between units.
How To Measure Without a Caliper
If you do not have a caliper, you can use a standard ruler with millimeter markings. A printable septum ring sizing chart is another option — many piercing studios offer these free online, and they work best when printed at 100% scale.
For gauge measurement without a caliper, place the ring’s bar against the ruler and count the millimeters across its width. This method is less precise because the curved ends of the ring can make the bar hard to align perfectly. You will get a close estimate, but you may be off by half a millimeter.
For diameter, lay the ring flat on a ruler and measure the inside distance from one inner edge to the other. Make sure the ring is lying flat and not tilted, or the measurement will be inaccurate.
If you already know your ring fits but want to confirm its size, you can also compare it against a known-size ring from a friend or a piercing studio.
Standard Septum Ring Sizes: Gauge and Diameter Chart
| Gauge (AWG) | Millimeters | Common Diameters | Typical Use |
|---|---|---|---|
| 18 gauge | 1.0 mm | 8–10 mm | Healed piercings preferring lighter jewelry |
| 16 gauge | 1.2 mm | 8–10 mm | Most common initial and healed septum size |
| 14 gauge | 1.6 mm | 8–10 mm | Stretched piercings or heavier jewelry |
| 12 gauge | 2.0 mm | 10–12 mm | Stretched piercings |
| 10 gauge | 2.5 mm | 10–12 mm | Significantly stretched piercings |
Most piercers use 16 gauge (1.2 mm) as the standard initial size for septum piercings. Diameters of 8 mm and 10 mm are the most common because they fit most anatomy while allowing the ring to sit comfortably below the columella, the tissue between your nostrils.
How To Determine Your Septum Ring Size If You Are Unsure
If you are buying your first septum ring or you lost the packaging from your current one, you have a few options. The most reliable method is to visit a professional piercer and ask them to measure your piercing. Most studios will do this at no charge, especially if you are purchasing jewelry from them.
You can also measure the jewelry you currently wear using the caliper method described above. If your current ring is comfortable and fits well, matching its measurements is your safest bet.
If you have a healing or recently pierced septum, do not remove the jewelry to measure it. Removing jewelry from a healing piercing can cause irritation or allow the hole to begin closing. Wait until the piercing is fully healed — typically several months — before changing or measuring jewelry.
What Happens If You Choose the Wrong Gauge or Diameter
Choosing the wrong gauge is more serious than choosing the wrong diameter. A ring that is too thick will not fit through the piercing hole and forcing it can tear the tissue or cause significant pain. A ring that is too thin can move excessively, irritate the piercing, and in some cases cause the hole to shrink over time.
Diameter problems are usually less severe but still uncomfortable. A ring with too small a diameter may press against the columella or feel tight. A ring with too large a diameter may hang too low, catch on clothing, or look disproportionate on your face.
If you are between sizes, choose the thinner gauge and the larger diameter. Both choices are safer and more comfortable than the alternatives.
Can You Measure Septum Ring Size With a String or Paper Strip?
You can measure the diameter with a piece of string or a thin strip of paper, but the method has limits. Wrap the string around the inside curve of the ring, mark where it overlaps, then lay it flat against a ruler to get the circumference. Divide that number by 3.14 (pi) to get the diameter.
This method works reasonably well for circular rings, but it becomes inaccurate for horseshoe or circular barbell styles because the curved shape does not form a perfect circle. For those shapes, a caliper is the only reliable tool.
Do not use this method to measure gauge. String and paper cannot measure thickness accurately.
Understanding Septum Ring Styles and How They Affect Measurement
Septum jewelry comes in several styles, and each one measures slightly differently. A seamless ring is a complete circle with no opening — you measure the inner diameter directly across. A horseshoe ring (also called a circular barbell) has two straight ends with balls or spikes — you measure the inner diameter the same way, but the overall length of the jewelry is longer than the diameter.
A clicker ring has a hinged segment that opens and closes. The hinge mechanism adds a small amount of material to one side, but the inner diameter measurement remains the standard way to size it. Captive bead rings have a small bead held in place by tension between the two open ends — the bead does not affect the gauge or diameter measurement.
When ordering online, always check whether the seller lists inner diameter or outer diameter. Most reputable sellers list inner diameter, but some list outer diameter, which will make the ring appear larger than it actually fits.
Tips for Accurate Measurement Every Time
- Measure the thickest part of the bar for gauge — never the decorative ends.
- Measure inner diameter, not outer diameter, unless the seller explicitly states otherwise.
- Clean the jewelry before measuring so debris does not add thickness.
- Take two measurements and average them for consistency.
- If the ring is bent or warped, do not measure it — replace it.
- When in doubt, ask a piercer. They see hundreds of septum piercings and can identify your size at a glance.
Accurate measurement prevents the most common septum jewelry problems: rings that do not fit, rings that irritate the piercing, and rings that fall out unexpectedly. Taking 60 seconds to measure correctly saves you the cost and frustration of ordering the wrong size.
Frequently Asked Questions
What is the most common septum ring gauge?
16 gauge (1.2 mm) is the most common size for septum piercings, both for initial piercing and healed jewelry. Some piercers use 14 gauge (1.6 mm) for larger anatomy or personal preference.
How do I know my septum ring size without measuring?
Visit a professional piercer and ask them to identify your size — most will do this free of charge. If you have a ring that fits comfortably, a caliper measurement of that ring will give you the exact numbers.
Is a 16 or 18 gauge septum ring bigger?
16 gauge is bigger. In the AWG system, smaller numbers indicate thicker metal, so 16 gauge (1.2 mm) is thicker than 18 gauge (1.0 mm).
How do I measure a horseshoe septum ring?
Measure the inner diameter across the widest part of the curve with a caliper, and measure the gauge on the straight bar section. The balls on the ends do not affect either measurement.
