UK ring size J ½
UK size J ½ is equivalent to US size 5, with an inside diameter of approximately 15.7 mm.
Inside diameter15.7 mm
Inside circumference49.3 mm
How to check UK size J 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 15.7 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.