What ring size is 18.5 mm?
A 18.5 mm inner diameter is a US 8.5 — UK Q½, EU 58, Japan 17.
- US
- 8.5
- UK
- Q½
- EU
- 58
- Japan
- 17
- Inner diameter, millimetres
- 18.5
- Circ mm
- 58.1
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See the full international ring size chart · Converter
Frequently asked questions
Is 18.5 mm a diameter or circumference?
On this page 18.5 mm is the inner diameter (the width across the inside of the ring). The matching inner circumference is about 58.1 mm.
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.