EU ring size 51.5
EU size 51.5 is equivalent to US size 6, with an inside diameter of approximately 16.5 mm.
Inside diameter16.5 mm
Inside circumference51.9 mm
How to check EU size 51.5
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 16.5 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.