UK ring size R ½
UK size R ½ is equivalent to US size 9, with an inside diameter of approximately 18.9 mm.
Inside diameter18.9 mm
Inside circumference59.5 mm
How to check UK size R ½
Measure the inside diameter of a ring that already fits the intended finger. Measure straight across the widest inside point—do not include the metal. Compare that measurement with 18.9 mm.
This is a jewellery-size conversion, not a guarantee of fit. Finger size changes with temperature and time of day; wide bands often need extra room.