What is the ring size of a 22mm ring?

According to an international ring size conversion chart, a 22.1mm (Inside diameter) ring is the equivalent to 12 3/4 in the U.S. and Canada. In the U.K., that would be Z + 1/2.

22.1mm is the closest to 22mm on the chart. The next closest size would be 21.89mm which is 12 1/2 (U.S.) or Z (U.K.)