Japanese Ring Size Guide

NIWAKA rings use Japanese sizes. We provide a ring size comparison chart to help you determine your Japanese ring size.

This page applies to NIWAKA jewelry and high jewelry.

For information about bridal rings, please visit the NIWAKA Online Store
Japanese Scale US Scale Inner Circumference Diameter
(JCS) (mm) (inches) (mm) (inches)
1 39.10 1.54 12.45 0.49
1 1/2 40.38 1.59 12.85 0.51
1 40.84 1.61 13.00 0.51
1.5 41.36 1.63 13.17 0.52
2 41.65 1.64 13.26 0.52
2 41.89 1.65 13.33 0.52
2.5 42.41 1.67 13.50 0.53
2 1/2 42.93 1.69 13.67 0.54
3 42.94 1.69 13.67 0.54
3.5 43.46 1.71 13.83 0.54
4 43.98 1.73 14.00 0.55
3 44.21 1.74 14.07 0.55
4.5 44.51 1.75 14.17 0.56
5 45.03 1.77 14.33 0.56
3 1/2 45.48 1.79 14.48 0.57
5.5 45.55 1.79 14.50 0.57
6 46.08 1.81 14.67 0.58
6.5 46.60 1.83 14.83 0.58
4 46.76 1.84 14.88 0.59
7 47.12 1.86 15.00 0.59
7.5 47.65 1.88 15.17 0.60
4 1/2 48.04 1.89 15.29 0.60
8 48.17 1.90 15.33 0.60
8.5 48.69 1.92 15.50 0.61
9 49.22 1.94 15.67 0.62
5 49.31 1.94 15.70 0.62
9.5 49.74 1.96 15.83 0.62
10 50.27 1.98 16.00 0.63
5 1/2 50.59 1.99 16.10 0.63
10.5 50.79 2.00 16.17 0.64
11 51.31 2.02 16.33 0.64
11.5 51.84 2.04 16.50 0.65
6 51.87 2.04 16.51 0.65
12 52.36 2.06 16.67 0.66
12.5 52.88 2.08 16.83 0.66
6 1/2 53.14 2.09 16.92 0.67
13 53.41 2.10 17.00 0.67
13.5 53.93 2.12 17.17 0.68
7 54.42 2.14 17.32 0.68
14 54.45 2.14 17.33 0.68
14.5 54.98 2.16 17.50 0.69
15 55.50 2.19 17.67 0.70
7 1/2 55.70 2.19 17.73 0.70
15.5 56.03 2.21 17.83 0.70
16 56.55 2.23 18.00 0.71
8 56.97 2.24 18.14 0.71
16.5 57.07 2.25 18.17 0.72
17 57.60 2.27 18.33 0.72
17.5 58.12 2.29 18.50 0.73
8 1/2 58.25 2.29 18.54 0.73
18 58.64 2.31 18.67 0.73
18.5 59.17 2.33 18.83 0.74
9 59.53 2.34 18.95 0.75
19 59.69 2.35 19.00 0.75
19.5 60.21 2.37 19.17 0.75
20 60.74 2.39 19.33 0.76
9 1/2 60.80 2.39 19.35 0.76
20.5 61.26 2.41 19.50 0.77
21 61.78 2.43 19.67 0.77
10 62.08 2.44 19.76 0.78
21.5 62.31 2.45 19.83 0.78
22 62.83 2.47 20.00 0.79
22.5 63.36 2.49 20.17 0.79
10 1/2 63.36 2.49 20.17 0.79
23 63.88 2.51 20.33 0.80
23.5 64.40 2.54 20.50 0.81
11 64.64 2.54 20.57 0.81
24 64.93 2.56 20.67 0.81
24.5 65.45 2.58 20.83 0.82
11 1/2 65.91 2.59 20.98 0.83
25 65.97 2.60 21.00 0.83
25.5 66.50 2.62 21.17 0.83
26 67.02 2.64 21.33 0.84
12 67.19 2.65 21.39 0.84
26.5 67.54 2.66 21.50 0.85
27 68.07 2.68 21.67 0.85
12 1/2 68.47 2.70 21.79 0.86
27.5 68.59 2.70 21.83 0.86
28 69.11 2.72 22.00 0.87
28.5 69.64 2.74 22.17 0.87
13 69.74 2.75 22.20 0.87
29 70.16 2.76 22.33 0.88
29.5 70.69 2.78 22.50 0.89
13 1/2 71.02 2.80 22.61 0.89
30 71.21 2.80 22.67 0.89