Size Studio
UK Ring Size I in US, EU and mm
A UK (and Australian) ring size I is about a US 4.25 and an EU 48, with an inside diameter of about 15.1 mm (47.5 mm around).
| US / CA | UK / AU | EU (ISO) | Japan | Inside diameter | Inside circumference |
|---|---|---|---|---|---|
| 4.25 | I | 48 | 7 | 15.1 mm | 47.5 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: HLarger: JOpen the full converterHow to measure yourself
Questions
What is ring size I in mm?
About 15.1 mm inside diameter, 47.5 mm around.
What is UK ring size I in US?
About US 4.25.
What is ring size I in EU?
EU 48.
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