How to Measure Hoop Earrings: A Complete Size Guide
Learning how to measure hoop earrings is actually easy. You just need to know where to measure, what the number means, and how it relates to your ear. Once you understand that, choosing between 10 mm, 20 mm, 30 mm, or 50 mm hoops becomes much easier.
Key Takeaways
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Hoop earrings are commonly measured in millimeters (mm).
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Inner diameter measures the open space inside the hoop.
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Outer diameter measures the hoop from outside edge to outside edge.
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A hoop's thickness affects its inner and outer diameter, so two hoops with the same outer diameter may have different openings.
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To measure your ear for a hoop, measure from the piercing hole to the edge of your earlobe.
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Don't assume a listed size such as 20 mm refers to the inner opening. Check the seller's measurement specifications.
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Gauge and hoop diameter are different measurements. Gauge describes jewelry thickness, not the overall size of the hoop.
How Are Hoop Earrings Measured?

Hoop earrings are measured in millimeters (mm). The measurement tells you how wide the hoop is from one side to the other. But there is one thing to watch for: some sellers measure the inside of the hoop, while others measure the outside.
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Inner Diameter: The inner diameter is the open space inside the hoop. It tells you how much room the hoop has for your ear.
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Outer Diameter: The outer diameter measures the hoop from its outside edge to the other outside edge. It tells you how big the whole hoop is.
The inner diameter tells you about the space inside the hoop. The outer diameter tells you about its overall size.
Why Does This Matter?
Let's say two hoops are listed as 20 mm. If one is thin and the other is thick, they won't have the same amount of space inside. The thicker hoop will have a smaller opening. So, don't just look at “20 mm” when buying hoops. Check whether the seller means inner diameter or outer diameter.
How to Measure Hoop Earrings You Already Own
If you already have a pair of hoops and want to know their size, you can measure them with a ruler. A measuring caliper can give you a more precise result, but it isn't necessary for a basic measurement.
How to Measure the Inner Diameter
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Lay the hoop flat.
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Find the widest part of the hoop.
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Place your ruler across the center.
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Measure from the inside edge to the opposite inside edge.
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Write down the measurement in millimeters.
That number is the hoop's inner diameter.
How to Measure the Outer Diameter
Follow the same steps, but measure from the outside edge to the opposite outside edge. That number is the hoop's outer diameter.
Don't Measure the Clasp
If your hoop has a hinge, clasp, or other closure, don't include it in the measurement. Measure the circular part of the hoop itself. For example, if the outside of the hoop measures 20 mm, you have a 20 mm outer diameter hoop. But its inner opening will be smaller because the metal takes up some of that space.
How to Measure Your Ear for Hoop Earrings
Measuring an existing hoop tells you its size. Measuring your ear helps you figure out what size hoop you may need. The easiest way is to measure the distance from your piercing hole to the edge of your earlobe.
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Step 1: Find Your Piercing: Look at the hole where you normally wear your hoop.
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Step 2: Measure to the Edge of Your Earlobe: Using a ruler, measure the straight-line distance from the center of the piercing hole to the edge of your earlobe.
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Step 3: Double the Measurement: Because a diameter goes all the way across a circle, double that number.
So, an inner diameter of about 16 mm would reach roughly from the piercing to the edge of the lobe. But this is only a starting point. You may want a smaller hoop for a snug look or a larger one if you want more space and movement.
Why Your Piercing Position Matters
Two people can have similar-sized ears but need different hoop sizes. Their piercing holes may sit at different distances from the edge of the earlobe. Your piercing position, lobe shape, hoop thickness, and the way you want the hoop to sit can all affect the size you choose.
Hoop Earring Size Chart
Hoop sizes can be hard to understand from a number alone. A 10 mm hoop and a 30 mm hoop may not sound different, but the difference is easy to see when you compare them side by side. The chart below gives you a quick idea of how common hoop sizes compare.
|
Hoop size |
Inches |
General size |
|
5 mm |
0.20 in |
Very small |
|
8 mm |
0.31 in |
Small |
|
10 mm |
0.39 in |
Small |
|
12 mm |
0.47 in |
Small |
|
15 mm |
0.59 in |
Small to medium |
|
20 mm |
0.79 in |
Medium |
|
25 mm |
0.98 in |
Medium to large |
|
30 mm |
1.18 in |
Large |
|
40 mm |
1.57 in |
Large |
|
50 mm |
1.97 in |
Very large |
Important: These size descriptions are only general visual guides. There is no single industry rule that says a particular number of millimeters must be called “small,” “medium,” or “large.”
Hoop Earring Size on the Ear

What is earring gauge?
As we discussed, diameter measures how big a space an earring has inside and how it is actually sized, as inner and outer diameter, but gauge is the thickness of the part that pierces through your piercing.
Earring Gauge Size Chart
|
Gauge |
Millimeters |
Common use |
|
22g |
0.6 mm |
Thin, delicate posts |
|
20g |
0.8 mm |
Standard lobe piercings, butterfly-back studs |
|
18g |
1.0 mm |
Standard lobe piercings, professional piercing needles |
|
16g |
1.2 mm |
Cartilage, helix, tragus, conch |
|
14g |
1.4 mm |
Some cartilage and body piercings |
|
12g |
1.6 mm |
Stretched piercings |
Note:
Remember, gauge works backward. The smaller the number, the thicker the post. A 16g earring is thicker than an 18g earring, even though 16 is a smaller number than 18. Most people with standard lobe piercings wear 20g or 18g without ever checking the label, since that's what butterfly-back studs and small hoops are typically made in.
Read About: Types Of Ear Piercings
How to Choose the Right Hoop Earring Size
For a snug everyday look
Smaller hoops sit close to the earlobe and barely move when you turn your head. This kind of fit works well for anyone who wears earrings all day, every day. A snug hoop also tends to catch less on hair, scarves, or phone calls.
For a classic medium hoop
Medium hoops strike a balance between visibility and ease. They're noticeable without dominating the face, and they tend to suit the widest range of face shapes and outfits. This size range is often the safest starting point if you're unsure what to buy.
For a statement hoop
Larger hoops are meant to be seen. They add movement, catch light differently than smaller styles, and naturally draw the eye toward the face. Statement hoops work well for occasions where you want the earrings to be part of the outfit's story, not just a quiet detail.
For small or high lobe piercings
If your piercing sits higher on the lobe or the lobe itself is on the smaller side, inner diameter becomes the number that matters most. A hoop with too much open space can feel loose or hang at an awkward angle. Checking inner diameter first, before outer diameter or overall style, helps avoid a hoop that never quite sits right.
For multiple ear piercings
Stacking hoops across multiple piercings adds a layer of planning that single-piercing shopping doesn't require. Smaller hoops generally sit closer to the ear and work well in tighter piercing clusters, while a single larger hoop can anchor the look from a lower or more prominent piercing. Spacing between piercings will often decide how many hoops can comfortably sit next to each other without overlapping.
