How to Measure Hoop Earrings: Inner vs Outer Diameter
How to Measure Hoop Earrings: Inner vs Outer Diameter
A hoop's size is one little number in millimetres — but it can mean two different things. Here's how hoop diameter is measured, and how to pick the size that's right for you.
Hoop earrings are measured by diameter, in millimetres. That figure usually refers to the outer diameter — the full width across the outside of the hoop, including the metal — though some listings give the inner diameter, the open space inside. For the same hoop, the outer diameter is always the larger of the two.
Buying hoops online comes down to trusting one small number. A hoop listed as "12mm" tells you its size — but 12mm of what? The outer edge, or the inside of the circle? It's a small distinction that changes how big the hoop actually looks on your ear, and once you know how it works, you'll never be surprised by a hoop again.
01 — The measurementWhat the diameter number means
Hoops are sized by diameter — the width straight across the circle — and it's given in millimetres. That's different from a chain or drop, which is measured by length; a hoop is a circle, so its size is how wide that circle is. A 12mm hoop and a 40mm hoop are the same shape, just very different scales.
Diameter is the standard, but there's a subtlety in which diameter a listing means, and that's where inner versus outer comes in.
02 — Inner vs outerThe distinction that matters
Every hoop has two diameters:
| Measurement | What it measures |
|---|---|
| Outer diameter | Across the full outside edge, including the metal band |
| Inner diameter | Across the open space inside the hoop |
The gap between them is twice the thickness of the band. On a fine, slim hoop that difference is tiny; on a thick, chunky hoop it can be a few millimetres — enough to matter. Most listings quote the outer diameter, because it reflects how large the hoop looks, but not all do.
The quick rule
If a listing doesn't say, assume the figure is the outer diameter. If the exact size is important — say you're matching an existing pair — ask the seller whether they measured inner or outer, and note the band thickness too.
03 — Choosing a sizeWhat different diameters look like
Once you know the number is a diameter, picking a size is easy. A rough guide by outer diameter:
| Diameter | Reads as |
|---|---|
| 8–12 mm | Small, hugs the lobe — everyday and layerable |
| 13–25 mm | Classic hoop with a little swing |
| 30 mm and up | Bolder, more statement |
A 12mm hoop sits at the small, snug end — larger than a tiny huggie but still understated, which makes it one of the most wearable everyday sizes. It's big enough to show a finish like colored enamel beautifully, small enough to wear from morning to night.
04 — ClosureHow small hoops fasten
Small hoops close in a few ways, and a secure closure matters most when the hoop is worn all day. A latch closure is a common, reliable choice — one end swings open and clicks firmly shut, holding the hoop closed without a separate back to lose. Whatever the closure, make sure it fastens with a definite click and check it now and then so a favourite pair stays put.
Burgundy Enamel Gold Hoop
A compact 12mm hoop in solid 14K gold, wrapped in deep burgundy red enamel, with a secure latch closure. Small enough for every day, with just enough size to let the glassy colour show — a hoop you can reach for constantly.
Small, snug, and rich with colour.
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