To measure a septum ring, you need two numbers: the gauge (thickness of the wire) and the internal diameter (how wide the ring is). Both are measured in millimeters, and the easiest way to get accurate readings is with a pair of digital calipers. If you already have a septum ring that fits well, measuring it takes about 30 seconds. If you’re buying your first piece of jewelry after a fresh piercing, your piercer’s initial jewelry gives you a starting point.
The Two Measurements That Matter
Every septum ring is defined by gauge and diameter. Gauge refers to how thick the metal wire or bar is. Most septum piercings use one of three standard gauges:
- 18G: 1.0 mm thick
- 16G: 1.2 mm thick
- 14G: 1.6 mm thick
The most common starting gauge for septum piercings is 16G or 14G. Inserting jewelry that’s thinner than your piercing hole can cause irritation over time, so knowing your gauge matters more than you might think.
Diameter is the distance across the inside of the ring, measured from one inner edge to the opposite inner edge. This is always the internal diameter, not the outside. Jewelry shops list their sizes this way, so measuring the outside of a ring will give you a number that’s too large and lead to a poor fit. Common septum diameters fall into two general ranges: 6 to 8 mm for a snug fit that sits close to the nose, and 10 to 12 mm for a looser fit that hangs lower.
How to Measure With Calipers
Digital calipers are the most reliable tool for this job. They’re inexpensive online and give you readings in millimeters, which is exactly what jewelry sizing uses. Before you start, close the caliper jaws completely and make sure the display reads zero. If it doesn’t, use the zero button to reset it.
To measure gauge, place the wire or bar of your ring between the caliper jaws and close them gently until they’re snug against the metal. The reading is your gauge in millimeters. You may get a number like 1.17 or 1.58 instead of a clean figure. Just round to the nearest tenth: 1.2 mm is 16G, 1.6 mm is 14G, 1.0 mm is 18G.
To measure internal diameter, hold the ring by its edge so you’re looking through it. Place the closed caliper jaws inside the ring at its center point, then open them until they press firmly against opposite inner edges. The number on the display is your internal diameter. This works the same way for clickers, seamless rings, segment rings, and captive bead rings. For horseshoe-style circular barbells, you still measure the internal diameter the same way, across the widest inner point between the two arms of the horseshoe.
Measuring Without Calipers
If you don’t have calipers, a ruler with millimeter markings can work in a pinch. Lay your ring flat on a table and measure across the inside opening at its widest point. This is less precise, especially for smaller rings where a single millimeter changes the fit noticeably, but it gets you in the right range. Avoid using a tape measure, which is too flexible to give a reliable reading on something this small.
Another option is to print a ring sizing guide from a jewelry retailer’s website and place your current ring over the circles until you find a match. These guides are only accurate if your printer doesn’t scale the image, so check the reference measurement printed on the page before you trust it.
What Happens When the Size Is Wrong
A ring with too small a diameter presses into the bottom of the nose between the nostrils. You’ll notice soreness on one or both sides of the piercing, particularly when you move your mouth, chew, or make facial expressions that pull the nose downward. Some people describe it as a sharp, stabbing pull, similar to a nose hair being yanked, that makes the eyes water immediately. If there’s no visible gap between the bottom of the ring and your skin, the diameter is likely too tight.
A ring that’s too large won’t cause pain, but it may stick out more than you want, catch on things, or shift around enough to slow healing on a newer piercing. For fresh piercings, your initial jewelry is typically sized slightly larger than your eventual preference to leave room for swelling. Once fully healed, you can size down for a closer fit.
Choosing Between Snug and Loose Fit
Your ideal diameter depends on your anatomy and the look you’re going for. A 6 to 8 mm internal diameter hugs the septum closely. This is the range most people choose for a subtle, everyday look or for jewelry they want to flip up and hide inside the nose. A 10 to 12 mm diameter creates a more visible dangle below the nostrils, which works well with statement pieces, stacked rings, or heavier decorative clickers.
If you’re between sizes, going one millimeter up is generally more comfortable than going one millimeter down. A slightly loose ring moves freely and doesn’t press against tissue, while a slightly tight ring creates constant low-grade pressure that can become genuinely painful over hours of wear. For horseshoe barbells specifically, the beads or ends on each arm add visual weight, so the ring may appear to sit lower than a seamless ring of the same diameter.