Inside diameter		Inside circumference		Sizes
(in)	(mm)	(in)	(mm)	US/Canada	UK/Ireland /Australia	Japan/ China	Switzerland
0.459	11.63	1.44	36.5	0
0.466	11.84	1.46	37.2	¼
0.474	12.04	1.49	37.8	½	A
0.482	12.24	1.51	38.5	¾	A½
0.49	12.45	1.54	39.1	1	B	1
0.498	12.65	1.56	39.7	1¼	B½
0.506	12.85	1.59	40.4	1½	C
0.514	13.06	1.61	41.0	1¾	C½
0.522	13.26	1.64	41.7	2	D	2	1.5
0.53	13.46	1.67	42.3	2¼	D½
0.538	13.67	1.69	42.9	2½	E	3	2.75
0.546	13.87	1.72	43.6	2¾	E½
0.554	14.07	1.74	44.2	3	F	4	4
0.562	14.27	1.77	44.8	3¼	F½	5	5.25
0.57	14.48	1.79	45.5	3½	G
0.578	14.68	1.82	46.1	3¾	G½	6	6.5
0.586	14.88	1.84	46.8	4	H	7
0.594	15.09	1.87	47.4	4¼	H½		7.75
0.602	15.29	1.89	48.0	4½	I	8
0.61	15.49	1.92	48.7	4¾	J		9
0.618	15.70	1.94	49.3	5	J½	9
0.626	15.90	1.97	50.0	5¼	K		10
0.634	16.10	1.99	50.6	5½	K½	10
0.642	16.31	2.02	51.2	5¾	L		11.75
0.65	16.51	2.04	51.9	6	L½	11	12.75
0.658	16.71	2.07	52.5	6¼	M	12
0.666	16.92	2.09	53.1	6½	M½	13	14
0.674	17.12	2.12	53.8	6¾	N
0.682	17.32	2.14	54.4	7	N½	14	15.25
0.69	17.53	2.17	55.1	7¼	O
0.698	17.73	2.19	55.7	7½	O½	15	16.5
0.706	17.93	2.22	56.3	7¾	P
0.714	18.14	2.24	57.0	8	P½	16	17.75
0.722	18.34	2.27	57.6	8¼	Q
0.73	18.54	2.29	58.3	8½	Q½	17
0.738	18.75	2.32	58.9	8¾	R		19
0.746	18.95	2.34	59.5	9	R½	18
0.754	19.15	2.37	60.2	9¼	S		20.25
0.762	19.35	2.39	60.8	9½	S½	19
0.77	19.56	2.42	61.4	9¾	T		21.5
0.778	19.76	2.44	62.1	10	T½	20
0.786	19.96	2.47	62.7	10¼	U	21
0.794	20.17	2.49	63.4	10½	U½	22	22.75
0.802	20.37	2.52	64.0	10¾	V
0.81	20.57	2.54	64.6	11	V½	23
0.818	20.78	2.57	65.3	11¼	W		25
0.826	20.98	2.59	65.9	11½	W½	24
0.834	21.18	2.62	66.6	11¾	X
0.842	21.39	2.65	67.2	12	X½	25	27.5
0.85	21.59	2.67	67.8	12¼	Y
0.858	21.79	2.70	68.5	12½	Z	26	28.75
0.866	22.00	2.72	69.1	12¾	Z½
0.874	22.20	2.75	69.7	13		27
0.882	22.40	2.77	70.4	13¼	Z1
0.89	22.61	2.80	71.0	13½
0.898	22.81	2.82	71.7	13¾	Z2
0.906	23.01	2.85	72.3	14	Z3
0.914	23.22	2.87	72.9	14¼
0.922	23.42	2.90	73.6	14½	Z4
0.93	23.62	2.92	74.2	14¾
0.938	23.83	2.95	74.8	15
0.946	24.03	2.97	75.5	15¼
0.954	24.23	3.00	76.1	15½
0.962	24.43	3.02	76.8	15¾
0.97	24.64	3.05	77.4	16