International Ring Size Conversion Chart

Britain	Europe	Japan	USA	Diameter Internal diameter in millimeters	Circumference Internal circumference in millimeters
.	.	.	0	11.54	36.25
A	.	.	.	11.90	37.38
.	.	0	.	12.00	37.70
A ½	.	.	.	12.10	38.01
B	.	.	.	12.30	38.64
.	.	.	1	12.37	38.86
B ½	.	.	.	12.50	39.27
.	.	.	1 ¼	12.58	39.52
C	.	.	.	12.70	39.90
.	0.15	.	1 ½	12.78	40.15
C ½	0.53	.	.	12.90	40.53
.	0.84	1	1 ¾	13.00	40.84
.	1.00	.	.	13.05	41.00
D	1.15	.	.	13.10	41.15
.	1.50	.	2	13.21	41.50
D ½	1.78	.	.	13.30	41.78
.	1.88	2	.	13.33	41.88
.	2.00	.	.	13.37	42.00
.	2.13	.	2 ¼	13.41	42.13
E	2.41	.	.	13.50	42.41
.	2.76	.	2 ½	13.61	42.76
.	2.91	3	.	13.66	42.91
E ½	3.00	.	.	13.69	43.00
.	3.42	.	2 ¾	13.82	43.42
F	3.67	.	.	13.90	43.67
.	3.98	4	.	14.00	43.98
.	4.00	.	.	14.01	44.00
.	4.14	.	3	14.05	44.14
Britain	Europe	Japan	USA	Diameter	Circumference
F ½	4.30	.	.	14.10	44.30
.	4.74	.	3 ¼	14.24	44.74
G	4.92	.	.	14.30	44.92
.	5.00	.	.	14.32	45.00
.	5.02	5	.	14.33	45.02
.	5.40	.	3 ½	14.45	45.40
G ½	5.55	.	.	14.50	45.55
.	6.00	.	.	14.64	46.00
.	6.02	.	3 ¾	14.65	46.02
.	6.06	6	.	14.66	46.06
H	6.18	.	.	14.70	46.18
.	6.68	.	4	14.86	46.68
H ½	6.81	.	.	14.90	46.81
.	7.00	.	.	14.96	47.00
.	7.12	7	.	15.00	47.12
.	7.34	.	4 ¼	15.07	47.34
I	7.44	.	.	15.10	47.44
.	7.97	.	4 ½	15.27	47.97
.	8.00	.	.	15.28	48.00
I ½	8.07	.	.	15.30	48.07
.	8.16	8	.	15.33	48.16
.	8.63	.	4 ¾	15.48	48.63
J	8.69	.	.	15.50	48.69
.	9.00	.	.	15.60	49.00
.	9.20	9	.	15.66	49.20
Britain	Europe	Japan	USA	Diameter	Circumference
J ½	9.32	.	5	15.70	49.32
K	9.95	.	5 ¼	15.90	49.95
.	10.00	.	.	15.92	50.00
.	10.27	10	.	16.00	50.27
K ½	10.58	.	5 ½	16.10	50.58
.	11.00	.	.	16.23	51.00
L	11.24	.	5 ¾	16.31	51.24
.	11.30	11	.	16.33	51.30
L ½	11.87	.	6	16.51	51.87
.	12.00	.	.	16.55	52.00
.	12.34	12	.	16.66	52.34
M	12.46	.	.	16.70	52.46
.	12.56	.	6 ¼	16.73	52.56
.	13.00	.	.	16.87	53.00
M ½	13.09	.	.	16.90	53.09
.	13.16	.	6 ½	16.92	53.16
.	13.41	13	.	17.00	53.41
N	13.72	.	.	17.10	53.72
.	13.85	.	6 ¾	17.14	53.85
.	14.00	.	.	17.19	54.00
N ½	14.35	.	.	17.30	54.35
.	14.44	14	.	17.33	54.44
.	14.51	.	7	17.35	54.51
O	14.98	.	.	17.50	54.98
.	15.00	.	7 ¼	17.56	55.00
.	15.48	15	.	17.66	55.48
Britain	Europe	Japan	USA	Diameter	Circumference
O ½	15.61	.	.	17.70	55.61
.	15.76	.	7 ½	17.75	55.76
.	16.00	.	.	17.83	56.00
P	16.23	.	.	17.90	56.23
.	16.45	.	7 ¾	17.97	56.45
.	16.55	16	.	18.00	56.55
P ½	16.86	.	.	18.10	56.86
.	17.00	.	.	18.14	57.00
.	17.15	.	8	18.19	57.15
Q	17.49	.	.	18.30	57.49
.	17.59	17	.	18.33	57.59
.	17.77	.	8 ¼	18.39	57.77
.	18.00	.	.	18.46	58.00
Q ½	18.12	.	.	18.50	58.12
.	18.40	.	8 ½	18.59	58.40
.	18.62	18	.	18.66	58.62
R	18.75	.	.	18.70	58.75
.	19.00	.	8 ¾	18.78	59.00
R ½	19.38	.	.	18.90	59.38
.	19.66	.	9	18.99	59.66
.	19.69	19	.	19.00	59.69
S	20.00	.	.	19.10	60.00
.	20.38	.	9 ¼	19.22	60.38
S ½	20.63	.	.	19.30	60.63
.	20.73	20	.	19.33	60.73
.	20.98	.	9 ½	19.41	60.98
.	21.00	.	.	19.42	61.00
Britain	Europe	Japan	USA	Diameter	Circumference
T	21.26	.	.	19.50	61.26
.	21.67	.	9 ¾	19.63	61.67
.	21.76	21	.	19.66	61.76
T ½	21.89	.	.	19.70	61.89
.	22.00	.	.	19.74	62.00
.	22.33	.	10	19.84	62.33
U	22.52	.	.	19.90	62.52
.	22.83	22	.	20.00	62.83
.	23.00	.	10 ¼	20.05	63.00
U ½	23.15	.	.	20.10	63.15
.	23.59	.	10 ½	20.24	63.59
V	23.77	.	.	20.30	63.77
.	23.87	23	.	20.33	63.87
.	23.99	.	..	20.37	63.99
.	24.28	.	10 ¾	20.46	64.28
V ½	24.40	..	..	20.50	64.40
.	24.91	24	.	20.66	64.91
.	24.97	.	11	20.68	64.97
W	25.00	.	.	20.69	65.00
.	25.60	.	11 ¼	20.88	65.60
W ½	25.66	.	.	20.90	65.66
.	25.97	25	.	21.00	65.97
.	26.00	.	.	21.01	66.00
.	26.22	.	11 ½	21.08	66.22
X	26.29	..	.	21.10	66.29
X ½	26.92	.	10 ¾	21.30	66.92
.	27.01	.	.	21.33	67.01
Y	27.51	.	12	21.49	67.51
.	28.02	.	.	21.65	68.02
.	28.05	27	.	21.66	68.05
Y ½	28.20	.	12 ¼	21.71	68.20
Z	28.77	.	12 ½	21.89	68.77
.	28.99	.	.	21.96	68.99
.	29.12	28	.	22.00	69.12
Britain	Europe	Japan	USA	Diameter	Circumference
Z ½	29.43	.	.	22.10	69.43
.	29.49	.	12 ¾	22.12	69.49
Z+1	29.99	.	.	22.28	69.99
.	30.15	29	13	22.33	70.15
Z+1 ½	30.69	.	.	22.50	70.69
.	30.81	.	13 ¼	22.54	70.81
.	31.00	.	.	22.60	71.00
.	31.19	30	.	22.66	71.19
Z+2	31.31	.	.	22.70	71.31
.	31.47	.	13 ½	22.75	71.47
Z+2 ½	32.01	.	13 ¾	22.92	72.01
.	32.26	31	.	23.00	72.26
Z+3	32.57	.	.	23.10	72.57
.	32.76	.	14	23.16	72.76
.	33.01	.	.	23.24	73.01
Z+3 ½	33.20	.	.	23.30	73.20
.	33.32	.	.	23.34	73.32
.	33.29	32	.	23.33	73.29
.	33.42	.	14 ¼	23.37	73.42
Z+4	33.83	.	.	23.50	73.83
.	33.98	.	14 ½	23.55	73.98
.	34.33	33	.	23.66	74.33
Z+4 ½	34.46	.	.	23.70	74.46
.	34.71	.	14 ¾	23.78	74.71
.	34.99	.	.	23.87	74.99
Z+5	35.08	.	.	23.90	75.08
.	35.40	34	15	24.00	75.40
Z+5 ½	35.71	.	.	24.10	75.71
.	36.00	.	15 ¼	24.19	76.00
Z+6	36.34	.	.	24.30	76.34
.	36.43	35	.	24.33	76.43
.	36.69	.	15 ½	24.41	76.69
Z+6 ½	37.00	.	.	24.51	77.00
.	37.31	.	15 ¾	24.61	77.31
.	37.47	36	.	24.66	77.47
Z+7	37.60	.	.	24.70	77.60
..	38.00	.	16	24.83	78.00
Z+7 ½	38.23	.	.	24.90	78.23
.	38.54	37	16 ¼	25.00	78.54

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International Ring Size Conversion Chart