Ring Sizes

Ring size (USA)	Inside diameter (mm)	Inside circumference (mm)
1/2	11.95	37.54
3/4	12.18	38.26
1	12.37	38.86
1 1/4	12.60	39.58
1 1/2	12.78	40.15
1 3/4	13.00	40.84
2	13.21	41.50
2 1/4	13.41	42.13
2 1/2	13.61	42.76
2 3/4	13.83	43.45
3	14.05	44.14
3 1/8	14.15	44.45
3 1/4	14.25	44.77
3 3/8	14.36	45.11
3 1/2	14.45	45.40
3 5/8	14.56	45.74
3 3/4	14.65	46.02
4	14.86	46.68
4 1/4	15.04	47.25
4 1/2	15.27	47.97
4 5/8	15.40	48.38
4 3/4	15.53	48.79
5	15.70	49.32
5 1/8	15.80	49.64
5 1/4	15.90	49.95
5 3/8	16.00	50.27
5 1/2	16.10	50.58
5 3/4	16.30	51.21
5 7/8	16.41	51.55
6	16.51	51.87
6 1/4	16.71	52.50
6 1/2	16.92	53.16
6 3/4	17.13	53.82
7	17.35	54.51
7 1/4	17.45	54.82
7 1/2	17.75	55.76
7 3/4	17.97	56.45
8	18.19	57.15
8 1/4	18.35	57.65
8 1/2	18.53	58.21
8 5/8	18.61	58.47
8 3/4	18.69	58.72
8 7/8	18.80	59.06
9	18.89	59.34
9 1/8	19.10	60.00
9 1/4	19.22	60.38
9 3/8	19.31	60.66
9 1/2	19.41	60.98
9 5/8	19.51	61.29
9 3/4	19.62	61.64
10	19.84	62.33
10 1/4	20.02	62.89
10 1/2	20.20	63.46
10 5/8	20.32	63.84
10 3/4	20.44	64.21
11	20.68	64.97
11 1/8	20.76	65.22
11 1/4	20.85	65.50
11 3/8	20.94	65.78
11 1/2	21.08	66.22
11 5/8	21.18	66.54
11 3/4	21.24	66.73
11 7/8	21.30	66.92
12	21.49	67.51
12 1/4	21.69	68.14
12 1/2	21.89	68.77
12 3/4	22.10	69.43
13	22.33	70.15
13 1/4	22.40	70.37
13 1/2	22.60	71.00
13 3/4	22.81	71.66
14	23.01	72.29
14 1/4	23.22	72.95
14 1/2	23.42	73.58
14 3/4	23.62	74.20
15	23.83	74.86
15 1/4	24.03	75.49
15 1/2	24.23	76.12
15 3/4	24.43	76.75
16	24.64	77.41
16 1/4	24.84	78.04
16 1/2	25.05	78.70
16 3/4	25.25	79.33
17	25.45	79.95