Ring Size Conversion Chart

USA	Diameter (mm)	Circumference (mm)	Diameter (inches)	Circumference (inches)	Britain	Europe	Japan
0	11.54	36.25	0.454	1.427
	11.9	37.38	0.469	1.472	A
	12	37.7	0.472	1.484			0
	12.1	38.01	0.476	1.496	A1/2
	12.3	38.64	0.484	1.521	B
1	12.37	38.86	0.487	1.53
	12.5	39.27	0.492	1.546	B1/2
1-1/4	12.58	39.52	0.495	1.556
	12.7	39.9	0.5	1.571	C
1-1/2	12.78	40.15	0.503	1.581		0.15
	12.9	40.53	0.508	1.596	C1/2	0.53
1-3/4	13	40.84	0.512	1.608		0.84	1
	13.05	41	0.514	1.614		1
	13.1	41.15	0.516	1.62	D	1.15
2	13.21	41.5	0.52	1.634		1.5
	13.3	41.78	0.524	1.645	D1/2	1.78
	13.33	41.88	0.525	1.649		1.88	2
	13.37	42	0.526	1.654		2
2-1/4	13.41	42.13	0.528	1.659		2.13
	13.5	42.41	0.531	1.67	E	2.41
2-1/2	13.61	42.76	0.536	1.683		2.76
	13.66	42.91	0.538	1.689		2.91	3
	13.69	43	0.539	1.693	E1/2	3
2-3/4	13.82	43.42	0.544	1.709		3.42
	13.9	43.67	0.547	1.719	F	3.67
	14	43.98	0.551	1.731		3.98	4
	14.01	44	0.552	1.732		4
3	14.05	44.14	0.553	1.738		4.14
	14.1	44.3	0.555	1.744	F1/2	4.3
3-1/4	14.24	44.74	0.561	1.761		4.74
	14.3	44.92	0.563	1.769	G	4.92
	14.32	45	0.564	1.772		5
	14.33	45.02	0.564	1.772		5.02	5
3-1/2	14.45	45.4	0.569	1.787		5.4
	14.5	45.55	0.571	1.793	G1/2	5.55
	14.64	46	0.576	1.811		6
3-3/4	14.65	46.02	0.577	1.812		6.02
	14.66	46.06	0.577	1.813		6.06	6
	14.7	46.18	0.579	1.818	H	6.18
4	14.86	46.68	0.585	1.838		6.68
	14.9	46.81	0.587	1.843	H1/2	6.81
	14.96	47	0.589	1.85		7
	15	47.12	0.591	1.855		7.12	7
4-1/4	15.07	47.34	0.593	1.864		7.34
	15.1	47.44	0.594	1.868	I	7.44
4-1/2	15.27	47.97	0.601	1.889		7.97
	15.28	48	0.602	1.89		8
	15.3	48.07	0.602	1.893	I1/2	8.07
	15.33	48.16	0.604	1.896		8.16	8
4-3/4	15.48	48.63	0.609	1.915		8.63
	15.5	48.69	0.61	1.917	J	8.69
	15.6	49	0.614	1.929		9
	15.66	49.2	0.617	1.937		9.2	9
5	15.7	49.32	0.618	1.942	J1/2	9.32
5-1/4	15.9	49.95	0.626	1.967	K	9.95
	15.92	50	0.627	1.969		10
	16	50.27	0.63	1.979		10.27	10
5-1/2	16.1	50.58	0.634	1.991	K1/2	10.58
	16.23	51	0.639	2.008		11
5-3/4	16.31	51.24	0.642	2.017	L	11.24
	16.33	51.3	0.643	2.02		11.3	11
6	16.51	51.87	0.65	2.042	L1/2	11.87
	16.55	52	0.652	2.047		12
	16.66	52.34	0.656	2.061		12.34	12
	16.7	52.46	0.657	2.065	M	12.46
6-1/4	16.73	52.56	0.659	2.069		12.56
	16.87	53	0.664	2.087		13
	16.9	53.09	0.665	2.09	M1/2	13.09
6-1/2	16.92	53.16	0.666	2.093		13.16
	17	53.41	0.669	2.103		13.41	13
	17.1	53.72	0.673	2.115	N	13.72
6-3/4	17.14	53.85	0.675	2.12		13.85
	17.19	54	0.677	2.126		14
	17.3	54.35	0.681	2.14	N1/2	14.35
	17.33	54.44	0.682	2.143		14.44	14
7	17.35	54.51	0.683	2.146		14.51
	17.5	54.98	0.689	2.165	O	14.98
7-1/4	17.56	55	0.691	2.165		15
	17.66	55.48	0.695	2.184		15.48	15
	17.7	55.61	0.697	2.189	O1/2	15.61
7-1/2	17.75	55.76	0.699	2.195		15.76
	17.83	56	0.702	2.205		16
	17.9	56.23	0.705	2.214	P	16.23
7-3/4	17.97	56.45	0.707	2.222		16.45
	18	56.55	0.709	2.226		16.55	16
	18.1	56.86	0.713	2.239	P1/2	16.86
	18.14	57	0.714	2.244		17
8	18.19	57.15	0.716	2.25		17.15
	18.3	57.49	0.72	2.263	Q	17.49
	18.33	57.59	0.722	2.267		17.59	17
8-1/4	18.39	57.77	0.724	2.274		17.77
	18.46	58	0.727	2.283		18
	18.5	58.12	0.728	2.288	Q1/2	18.12
8-1/2	18.59	58.4	0.732	2.299		18.4
	18.66	58.62	0.735	2.308		18.62	18
	18.7	583/4	0.736	#VALUE!	R	183/4
8-3/4	18.78	59	0.739	2.323		19
	18.9	59.38	0.744	2.338	R1/2	19.38
9	18.99	59.66	0.748	2.349		19.66
	19	59.69	0.748	2.35		19.69	19
	19.1	60	0.752	2.362	S	20
9-1/4	19.22	60.38	0.757	2.377		20.38
	19.3	60.63	0.76	2.387	S1/2	20.63
	19.33	60.73	0.761	2.391		20.73	20
9-1/2	19.41	60.98	0.764	2.401		20.98
	19.42	61	0.765	2.402		21
	19.5	61.26	0.768	2.412	T	21.26
9-3/4	19.63	61.67	0.773	2.428		21.67
	19.66	61.76	0.774	2.431		21.76	21
	19.7	61.89	0.776	2.437	T1/2	21.89
	19.74	62	0.777	2.441		22
10	19.84	62.33	0.781	2.454		22.33
	19.9	62.52	0.783	2.461	U	22.52
	20	62.83	0.787	2.474		22.83	22
10-1/4	20.05	63	0.789	2.48		23
	20.1	63.15	0.791	2.486	U1/2	23.15
10-1/2	20.24	63.59	0.797	2.504		23.59
	20.3	63.77	0.799	2.511	V	23.77
	20.33	63.87	0.8	2.515		23.87	23
	20.37	63.99	0.802	2.519		23.99
10-3/4	20.46	64.28	0.806	2.531		24.28
	20.5	64.4	0.807	2.535	V1/2	24.4
	20.66	64.91	0.813	2.556		24.91	24
11	20.68	64.97	0.814	2.558		24.97
	20.69	65	0.815	2.559	W	25
11-1/4	20.88	65.6	0.822	2.583		25.6
	20.9	65.66	0.823	2.585	W1/2	25.66
	21	65.97	0.827	2.597		25.97	25
	21.01	66	0.827	2.598		26
11-1/2	21.08	66.22	0.83	2.607		26.22
	21.1	66.29	0.831	2.61	X	26.29
10-3/4	21.3	66.92	0.839	2.635	X1/2	26.92
	21.33	67.01	0.84	2.638		27.01	26
12	21.49	67.51	0.846	2.658	Y	27.51
	21.65	68.02	0.852	2.678		28.02
	21.66	68.05	0.853	2.679		28.05	27
12-1/4	21.71	68.2	0.855	2.685	Y1/2	28.2
12-1/2	21.89	68.77	0.862	2.707	Z	28.77
	21.96	68.99	0.865	2.716		28.99
	22	69.12	0.866	2.721		29.12	28
	22.1	69.43	0.87	2.733	Z1/2	29.43
12-3/4	22.12	69.49	0.871	2.736		29.49
	22.28	69.99	0.877	2.756	Z+1	29.99
13	22.33	70.15	0.879	2.762		30.15	29
	22.5	70.69	0.886	2.783	Z+11/2	30.69
13-1/4	22.54	70.81	0.887	2.788		30.81
	22.6	71	0.89	2.795		31
	22.66	71.19	0.892	2.803		31.19	30
	22.7	71.31	0.894	2.807	Z+2	31.31
13-1/2	22.75	71.47	0.896	2.814		31.47
13-3/4	22.92	72.01	0.902	2.835	Z+21/2	32.01
	23	72.26	0.906	2.845		32.26	31
	23.1	72.57	0.909	2.857	Z+3	32.57
14	23.16	72.76	0.912	2.865		32.76
	23.24	73.01	0.915	2.874		33.01
	23.3	73.2	0.917	2.882	Z+31/2	33.2
	23.34	73.32	0.919	2.887		33.32
	23.33	73.29	0.919	2.885		33.29	32
14-1/4	23.37	73.42	0.92	2.891		33.42
	23.5	73.83	0.925	2.907	Z+4	33.83
14-1/2	23.55	73.98	0.927	2.913		33.98
	23.66	74.33	0.931	2.926		34.33	33
	23.7	74.46	0.933	2.931	Z+41/2	34.46
14-3/4	23.78	74.71	0.936	2.941		34.71
	23.87	74.99	0.94	2.952		34.99
	23.9	75.08	0.941	2.956	Z+5	35.08
15	24	75.4	0.945	2.969		35.4	34
	24.1	75.71	0.949	2.981	Z+51/2	35.71
15-1/4	24.19	76	0.952	2.992		36
	24.3	76.34	0.957	3.006	Z+6	36.34
	24.33	76.43	0.958	3.009		36.43	35
15-1/2	24.41	76.69	0.961	3.019		36.69
	24.51	77	0.965	3.031	Z+61/2	37
15-3/4	24.61	77.31	0.969	3.044		37.31
	24.66	77.47	0.971	3.05		37.47	36
	24.7	77.6	0.972	3.055	Z+7	37.6
16	24.83	78	0.978	3.071		38
	24.9	78.23	0.98	3.08	Z+71/2	38.23
16-1/4	25	78.54	0.984	3.092		38.54	37