What ring size is 21.5 mm?
A 21.5 mm inner diameter is a US 12.5 — UK Z, EU 68, Japan 26. (between sizes — we suggest sizing up)
- US
- 12.5
- UK
- Z
- EU
- 68
- Japan
- 26
- Inner diameter, millimetres
- 21.5
- Circ mm
- 67.5
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See the full international ring size chart · Converter
Frequently asked questions
Is 21.5 mm a diameter or circumference?
On this page 21.5 mm is the inner diameter (the width across the inside of the ring). The matching inner circumference is about 67.5 mm.
I am between sizes — should I size up or down?
Measure again at a different time. If the result stays between sizes, compare band width, knuckle clearance, and the retailer's chart before choosing. A wider band can feel tighter than a narrow one at the same labelled size.
How should I confirm a converted ring size before ordering?
Measure the same finger or a ring that fits with a second method. For an expensive, wide, or non-resizable ring, check the retailer's chart and confirm with a physical sizer or jeweller.