UK ring size X ½
UK size X ½ is equivalent to US size 12, with an inside diameter of approximately 21.4 mm.
Inside diameter21.4 mm
Inside circumference67.2 mm
How to check UK size X 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 21.4 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.