Inside Diameter		Inside Circumference		Sizes
MM	Inches	MM	Inches	British & Australian	US & Canada	French & Russian	German	Japanese	Swiss
14.05	0.553	44.14	1.74	G	3 3/8	45 1/4	-	5	5 1/4
14.15	0.557	44.45	1.75	G 1/4	3 1/2	-	14 1/2	-	-
14.25	0.561	44.77	1.76	G 1/2	3 5/8	-	-	6	-
14.36	0.565	45.11	1.77	G 3/4	3 3/4	46 1/2	-	-	6 1/2
14.45	0.569	45.40	1.79	H	4	-	15	7	-
14.56	0.573	45.74	1.80	H 1/2	4 1/8	47 3/4	-	-	7 3/4
14.65	0.577	46.02	1.81	I	4 1/4	-	15 1/4	8	-
14.86	0.585	46.68	1.84	I 1/2	4 1/2	49	15 1/2	-	9
15.04	0.592	47.25	1.86	J	4 5/8	-	-	9	-
15.27	0.601	47.97	1.89	J 1/2	4 3/4	-	15 3/4	-	-
15.40	0.606	48.38	1.90	K	5 1/8	50	-	-	10
15.53	0.611	48.79	1.92	K 1/4	5 1/4	-	-	-	-
15.70	0.618	49.32	1.94	K 1/2	5 3/8	-	16	10	-
15.80	0.622	49.64	1.95	L	5 1/2	51 3/4	-	-	11 3/4
15.90	0.626	49.95	1.97	L 1/4	5 3/4	-	-	-	-
16.00	0.630	50.27	1.98	L 1/2	5 7/8	-	-	10	-
16.10	0.634	50.58	1.99	M	6	52 3/4	16 1/2	12	12 3/4
16.30	0.642	51.21	2.02	M 1/2	6 1/4	-	-	-	-
16.41	0.646	51.55	2.03	N	6 1/2	54	17	13	14
16.51	0.650	51.87	2.04	N 1/2	6 3/4	-	-	-	-
16.71	0.658	52.50	2.07	O	7	55 1/4	17 1/4	14	15 1/4
16.92	0.666	53.16	2.09	O 1/2	7 1/4	-	-	-	-
17.13	0.674	53.82	2.12	P	7 1/2	56 1/2	17 3/4	15	16 1/2
17.35	0.683	54.51	2.15	P 1/2	7 3/4	-	-	-	-
17.45	0.687	54.82	2.16	Q	8	57 3/4	18	16	17 3/4
17.75	0.699	55.76	2.20	Q 1/2	8 1/4	-	-	-	-
17.97	0.707	56.45	2.22	Q 3/4	8 1/2	-	18 1/2	17	-
18.19	0.716	57.15	2.25	R	8 5/8	59	-	-	19
18.35	0.722	57.65	2.27	R 1/4	8 3/4	-	-	-	-
18.53	0.729	58.21	2.29	R 1/2	8 7/8	-	-	-	-
18.61	0.733	58.47	2.30	R 3/4	9	-	19	18	-
18.69	0.736	58.72	2.31	S	9 1/8	60 1/4	-	-	20 1/4
18.80	0.740	59.06	2.32	S 1/4	9 1/4	-	-	-	-
18.89	0.748	59.34	2.35	S 1/2	9 3/8	-	-	-	-
19.10	0.752	60.00	2.36	S 3/4	9 1/2	-	19 1/2	19	-
19.22	0.757	60.38	2.38	T	9 5/8	61 1/2	-	-	21 1/2
19.31	0.760	60.66	2.39	T 1/4	9 3/4	-	-	-	-
19.41	0.764	60.98	2.40	T 1/2	10	-	20	20	-
19.51	0.768	61.29	2.41	U	10 1/4	62 3/4	-	21	22 3/4
19.62	0.772	61.64	2.43	U 1/2	10 1/2	-	20 1/4	22	-
19.84	0.781	62.33	2.45	V	10 5/8	63	-	-	23 3/4
20.02	0.788	62.89	2.48	V 1/2	10 3/4	-	-	-	-
20.20	0.797	63.46	2.50	V 1/2	11	-	20 3/4	23	25
20.32	0.800	63.84	2.51	W	11 1/8	65	-	-	-
20.44	0.805	64.21	2.53	W 1/4	11 1/4	-	-	24	-
20.68	0.814	64.97	2.56	W 1/2	11 3/8	-	21	-	-
20.76	0.817	65.22	2.57	W 3/4	11 1/2	-	-	-	-
20.85	0.821	65.50	2.58	X	11 5/8	66 1/4	-	-	26 1/4
20.94	0.824	65.78	2.59	X 1/4	11 3/4	-	-	-	-
21.08	0.830	66.22	2.61	X 1/2	11 7/8	-	-	-	-
21.18	0.834	66.54	2.62	Y	12	67 1/2	21 1/4	25	27 1/2
21.24	0.836	66.73	2.63	Y 1/4	12 1/4	-	-	-	-
21.30	0.839	66.92	2.64	Y 1/2	12 1/2	-	-	-	-
21.49	0.846	67.51	2.66	Z	12 3/4	68 3/4	21 3/4	26	28 3/4
21.69	0.854	68.14	2.68	Z+1	13	-	22	27	-
21.89	0.862	68.77	2.71	-	-	-	-	-	-
22.10	0.870	69.43	2.73	-	-	-	-	-	-
22.33	0.879	70.15	2.76	-	-	-	-	-	-