Size Studio
UK Ring Size O in US, EU and mm
A UK (and Australian) ring size O is about a US 7.25 and an EU 55, with an inside diameter of about 17.5 mm (55 mm around).
| US / CA | UK / AU | EU (ISO) | Japan | Inside diameter | Inside circumference |
|---|---|---|---|---|---|
| 7.25 | O | 55 | 15 | 17.5 mm | 55 mm |
Good to know
- EU (ISO) ring sizes are the inside circumference in millimetres. US sizes go up about 0.8 mm in diameter per whole size, UK letters about 0.4 mm.
- Fingers swell when warm. Measure at the end of the day, and go half a size up for wide bands.
Sizes either side
Smaller: NLarger: POpen the full converterHow to measure yourself
Questions
What is ring size O in mm?
About 17.5 mm inside diameter, 55 mm around.
What is UK ring size O in US?
About US 7.25.
What is ring size O in EU?
EU 55.
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