International Ring Size Conversion Chart

Sizes		Inside Diameter		Inside Circumference
US & CA	UK&AU	MM	Inches	MM	Inches
9.0	R 3/4	18.9	0.75	59.3	2.35
9.5	S 3/4	19.4	0.76	61.0	2.40
10.0	T 1/2	19.8	0.78	62.3	2.45
10.5	U 1/2	20.2	0.80	63.5	2.50
11.0	V 1/2	20.7	0.81	65.0	2.56
11.5	W 3/4	21.0	0.83	66.2	2.61
12.0	Y	21.5	0.85	67.5	2.66
12.5	Z	21.9	0.86	68.8	2.71
13.0	Z+1	22.33	0.88	70.2	2.76