International Ring Size Conversion Chart

Circumference (mm) Europe / ISO	Diameter (mm)	USA / Canada	UK / Australia	Asia	Switzerland
44.2	14.1	3	F	4	4
44.8	14.3		F-1/2	5	5-1/4
45.5	14.5	3-1/2	G
46.1	14.7		G-1/2	6	6-1/2
46.8	14.9	4	H	7
47.4	15.1		H-1/2		7-3/4
48.0	15.3	4-1/2	I	8
48.7	15.5		J		9
49.3	15.7	5	J-1/2	9
50.0	15.9		K		10
50.6	16.1	5-1/2	K-1/2	10
51.2	16.3		L		11-3/4
51.9	16.5	6	L-1/2	11	12-3/4
52.5	16.7		M	12
53.1	16.9	6-1/2	M-1/2	13	14
53.8	17.1		N
54.4	17.3	7	N-1/2	14	15-1/4
55.1	17.5		O
55.7	17.7	7-1/2	O-1/2	15	16-1/2
56.3	17.9		P
57.0	18.1	8	P-1/2	16	17-3/4
57.6	18.3		Q
58.3	18.5	8-1/2	Q-1/2	17
58.9	18.8		R		19
59.5	19.0	9	R-1/2	18
60.2	19.2		S		20-1/4
60.8	19.4	9-1/2	S-1/2	19
61.4	19.6		T		21-1/2
62.1	19.8	10	T-1/2	20
62.7	20.0		U	21
63.4	20.2	10-1/2	U-1/2	22	22-3/4
64.0	20.4		V
64.6	20.6	11	V-1/2	23
65.3	20.8		W		25
65.9	21.0	11-1/2	W-1/2	24
66.6	21.2		X
67.2	21.4	12	X-1/2	25	27-1/2
67.8	21.6		Y
68.5	21.8	12-1/2	Z	26	28-3/4
69.1	22.0		Z-1/2
69.7	22.2	13		27
70.4	22.4		Z + 1
71.0	22.6	13-1/2