What is ring size 12 in mm?

US ring size 12 is 21.4 mm inner diameter and 67.2 mm circumference (EU 67.2, UK X½, Japan 25).

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Ring size 12 in mm

Inner Ø21.4mm

Circumference67.2mm = EU/ISO

UKX½

JP · CN25

IT · ES · CH27.2

US ring size 12 has an inner diameter of 21.4 mm and an inner circumference of 67.2 mm. The EU/ISO size is that circumference (67.2); in the UK it’s X½, in Japan/China 25, and in Italy/Spain/Switzerland 27.2 (circumference minus 40). Not sure of your size? Measure a ring you own with the on-screen ring sizer.