Conversion Chart For Ring Size

US, UK, Japan, and Italy Sizes

US Size	Inside Diameter (in)	Inside Diameter (mm)	Inside Circumference (in)	Inside Circumference (mm)	UK Size	Japan Size	Italy Size
3	0.554	14.07	1.74	44.2	F	4	4.25
3.25	0.562	14.27	1.77	44.8	F 1/2	5	4.75
3.5	0.57	14.48	1.79	45.5	G	6	5.5
3.75	0.578	14.68	1.82	46.1	G 1/2	7	6
4	0.586	14.88	1.84	46.8	H	7	6.75
4.25	0.594	15.09	1.87	47.4	H 1/2	8	7.5
4.5	0.602	15.29	1.89	48.0	I	8	8
4.75	0.61	15.49	1.92	48.7	I 1/2	9	8.75
5	0.618	15.7	1.94	49.3	J	9	9.25
5.25	0.626	15.9	1.97	50.0	J 1/2	10	10
5.5	0.634	16.1	1.99	50.6	K	10	10.5
5.75	0.642	16.31	2.02	51.2	K 1/2	11	11.25
6	0.65	16.51	2.04	51.9	L	11	11.75
6.25	0.658	16.71	2.07	52.5	L 1/2	12	12.5
6.5	0.666	16.92	2.09	53.1	M	13	13
6.75	0.674	17.12	2.12	53.8	M 1/2	13	13.75
7	0.682	17.32	2.14	54.4	N	14	14.5
7.25	0.69	17.53	2.17	55.1	N 1/2	15	15
7.5	0.698	17.73	2.19	55.7	O	15	15.75
7.75	0.706	17.93	2.22	56.3	P	16	16.25
8	0.714	18.14	2.24	57.0	P 1/2	16	17
8.25	0.722	18.34	2.27	57.6	Q	17	17.5
8.5	0.73	18.54	2.29	58.3	Q 1/2	17	18.25
8.75	0.738	18.75	2.32	58.9	R	18	19
9	0.746	18.95	2.34	59.5	R 1/2	18	19.5
9.25	0.754	19.15	2.37	60.2	S	19	20.25
9.5	0.762	19.35	2.39	60.8	S 1/2	19	21
9.75	0.77	19.56	2.42	61.4	T	20	21.5
10	0.778	19.76	2.44	62.1	T 1/2	20	22.25
10.25	0.786	19.96	2.47	62.7	U	21	23
10.5	0.794	20.17	2.49	63.4	U 1/2	22	23.5
10.75	0.802	20.37	2.52	64.0	V	22	24.25
11	0.81	20.57	2.54	64.6	V 1/2	23	25
11.25	0.818	20.78	2.57	65.3	W	24	25.5
11.5	0.826	20.98	2.59	65.9	W 1/2	24	26.25
11.75	0.834	21.18	2.62	66.6	X	25	27
12	0.842	21.39	2.64	67.2	X 1/2	25	27.75
12.25	0.85	21.59	2.67	67.8	Y	26	28.5
12.5	0.858	21.79	2.69	68.5	Z	27	29
12.75	0.866	22.00	2.72	69.1	Z 1/2	27	29.75
13	0.874	22.20	2.75	69.7	Z+1	28	30.5
13.25	0.882	22.40	2.77	70.4	Z+1	28	31.25
13.5	0.89	22.61	2.80	71.0	Z+1	29	32
13.75	0.898	22.81	2.82	71.7	Z+1	29	32.75
14	0.906	23.01	2.85	72.3	Z+2	30	33.5
14.25	0.914	23.22	2.87	72.9	Z+2	30	34.25
14.5	0.922	23.42	2.90	73.6	Z+2	31	35
14.75	0.93	23.62	2.92	74.2	Z+2	31	35.75
15	0.938	23.83	2.95	74.8	Z+3	32	36.5
15.25	0.946	24.03	2.97	75.5	Z+3	33	37.25
15.5	0.954	24.23	3.00	76.1	Z+3	33	38
15.75	0.962	24.44	3.02	76.7	Z+3	34	38.75
16	0.97	24.64	3.05	77.4	Z+4	34	39.5