How to Measure Your Earring Size: A Simple Guide to Millimeters and Gauge

Quick Answer

To measure your earring size, you'll need to know two key numbers: the gauge (thickness of the post) and the diameter or length of the earring top. For flat back earrings, check the post gauge (like 20g or 18g) and post length; for hoops, measure the external diameter. Use a ruler or caliper for accuracy, and refer to a size chart to convert mm to gauge.

Finding the right earring size is the difference between a comfortable, secure fit and a sore ear. Whether you're buying flat back earrings for a new cartilage piercing or choosing hoop earrings for your lobes, understanding millimeters and gauge is essential. This guide breaks down how to measure earring size, explains the numbers you'll see on product pages, and helps you avoid common sizing mistakes.

We'll cover the two main measurements: the gauge (post thickness) and the millimeter size (diameter or length). You'll learn how to measure existing earrings, what to look for in product descriptions, and why sizing matters for different piercing types. By the end, you'll be confident choosing earrings that fit well and feel great.

Understanding Earring Gauge and Millimeter Measurements

Earring size is described by two numbers: gauge and millimeter. Gauge (g) measures the thickness of the post that goes through your ear. Common gauges are 20g (0.8mm), 18g (1.0mm), and 16g (1.2mm). The millimeter measurement refers to the size of the earring top—its diameter for studs or the external diameter for hoops. For example, a flat back earring might have a 3mm top and a 20g post.

Why does this matter? If the gauge is too thick, the earring won't fit through your piercing. If it's too thin, the earring may move around and irritate the piercing. Similarly, the top size affects comfort and style: a 3mm top is subtle and great for stacking, while a 6mm top makes a bolder statement. Always check both measurements before buying, especially for cartilage earrings.

• Gauge is the thickness of the post, not the size of the decorative top.
• Millimeter size for studs is the diameter of the top; for hoops, it's the external diameter.
• Common gauges: 20g (0.8mm), 18g (1.0mm), 16g (1.2mm).

How to Measure Your Existing Earrings

If you have earrings that fit well, you can measure them to find your size. For a stud or flat back earring, measure the diameter of the top (the part that shows) using a ruler or caliper. For the post gauge, you'll need a caliper to measure the thickness of the post in millimeters, then convert to gauge using a chart. If you don't have a caliper, you can compare your earring to a reference image on a size chart.

For hoop earrings, measure the external diameter across the widest point. This is the number you'll see in product descriptions, like 14mm or 26mm. Remember that the internal diameter (the space inside the hoop) is what determines how snugly the hoop fits around your ear. If the external diameter is 14mm, the internal diameter will be smaller—for example, 11.5mm for a 14mm hoop.

• Use a caliper for accurate gauge measurement; a ruler works for top diameter.
• For hoops, measure the external diameter from edge to edge.
• Check if the product lists internal diameter as well—it affects fit.

Using an Earring Size Chart for Flat Back Earrings

Flat back earrings, like those used for cartilage piercings, come in specific sizes. The post gauge and length are crucial for a comfortable fit. A post that's too long will poke and catch on things; too short and it may not accommodate swelling or your ear's thickness. For example, the Sphere Push Pin Flat Back Earring offers post lengths of 6mm or 8mm, and gauges of 16g, 18g, or 20g. Choose a length based on your piercing—shorter for lobes, longer for thicker cartilage.

When looking at a size chart, match the gauge to your piercing. Standard lobe piercings are usually 20g or 18g, while cartilage piercings (like conch or rook) often use 16g or 18g. If you're unsure, visit a piercer to have your gauge measured. For flat back earrings, the top size (like 3mm) is a matter of style, but the post gauge and length are fit-critical.

• Flat back earring size includes top diameter, post gauge, and post length.
• Post length 6mm is typical for lobes; 8mm for thicker cartilage.
• When in doubt, get your gauge measured by a professional piercer.

Choosing Hoop Earring Diameter by Ear Placement

Hoop earrings are sized by their external diameter, which determines how much they stand out from your ear. For a subtle everyday look, a 12mm huggie hoop sits close to the ear, while a 14mm hoop adds a bit more presence. Larger hoops, like 26mm, make a bold statement and are often worn on the lobe. The internal diameter is also important—it should be large enough to fit comfortably around the earlobe without squeezing.

For cartilage hoops, the diameter needs to match the piercing location. A rook piercing, for example, might need a smaller hoop, while a conch can accommodate a larger one. Always check the product's internal diameter if listed. For example, the Bold Hoops, 14mm has an internal diameter of 11.5mm, which is designed to fit a standard lobe comfortably. If you're buying hoops for a new piercing, wait until it's fully healed before changing to a hoop.

• External diameter is the overall size of the hoop; internal diameter affects fit.
• Huggie hoops (12mm) are close-fitting; larger hoops (14mm+) are more noticeable.
• For cartilage, choose a hoop diameter that matches the piercing's location and healing stage.

Common Earring Sizing Mistakes to Avoid

One common mistake is confusing gauge with top size. A 20g post can have a 6mm top, and that's fine—the top size is about style, not fit. Another mistake is assuming all earrings with the same gauge will fit the same way. The post length also matters, especially for flat back earrings. If the post is too short, the back may not sit flush; too long, and it will be uncomfortable.

Also, don't guess your gauge. If you've had your ears pierced, ask your piercer for the gauge used. Many standard lobe piercings are 20g, but some piercing guns use 18g or even 16g. Using a size chart to convert mm to gauge is helpful, but measuring your actual piercing is the most reliable method. And remember, when in doubt, choose a slightly longer post for healing piercings to accommodate swelling.

• Gauge and top size are independent measurements.
• Always check post length for flat back earrings.
• Ask your piercer for your exact gauge if you're unsure.

Step-by-Step: Measuring Your Earring Size

1. Gather your tools: Get a ruler or caliper. A caliper is best for measuring post gauge in millimeters. If you only have a ruler, use the millimeter markings for top diameter. Checkpoint: A caliper gives the most accurate gauge measurement.
2. Measure the gauge of your current earring: If you have a well-fitting earring, measure the thickness of the post with calipers. Convert the millimeter reading to gauge using a chart (e.g., 0.8mm = 20g). If you don't have calipers, compare to a reference or ask your piercer. Checkpoint: Knowing your gauge prevents buying earrings that won't fit.
3. Measure the top diameter for studs: For studs or flat back earrings, measure the diameter of the decorative top in millimeters. This is the 'mm' size you see in product names, like 3mm. Checkpoint: Top size is about style, not fit—but it affects how the earring looks on your ear.
4. Measure hoop external diameter: For hoops, measure the external diameter from one outer edge to the other. Also check the internal diameter if listed, as it determines how the hoop fits around your ear. Checkpoint: A 14mm external hoop has a smaller internal diameter—always check both.
5. Check post length for flat backs: For flat back earrings, the post length (e.g., 6mm or 8mm) must match your ear thickness. If the post is too short, the back won't sit flush; too long, and it will be uncomfortable. Checkpoint: Choose 6mm for lobes, 8mm for thicker cartilage.
6. Use a size chart to confirm: Refer to an earring size chart to verify your measurements and conversions. Many charts list gauge, mm, and common uses (e.g., 20g for lobes, 16g for cartilage). Checkpoint: When in doubt, a professional piercer can measure your piercing size accurately.

Earring Sizes in Practice

• Sphere Push Pin Flat Back Earring, 3mm: Available in gauges 16g, 18g, or 20g and post lengths 6mm or 8mm. Best for healed cartilage or lobe piercings. This shows how flat back earrings come in multiple gauge and length options, so you can match your piercing exactly for comfort.
• Bold Hoops, 14mm: External diameter 14mm, internal diameter 11.5mm, width 3mm, post gauge 20g, best for first or second lobe. The internal diameter is key for lobe hoops—it tells you how snugly the hoop will fit, and 20g is standard for lobes.
• Gaia Ball Back Earrings in 14k Gold: Earring top 6mm tall x 3mm wide, post gauge 20g (0.8mm), screw-on ball back. The top size and post gauge together determine the look and fit; the screw-on design adds security for kids and daily wear.

Measuring your earring size doesn't have to be complicated. Focus on the two key numbers—gauge and millimeter—and use a size chart to guide you. Whether you're buying flat back earrings or hoops, checking the post gauge, length, and diameter ensures a comfortable fit that you can wear all day. With these tips, you'll shop with confidence and avoid the frustration of earrings that don't fit.