All rings are labeled in standard JP sizes known as JCS (Japan Custom Size). Please measure the length around your finger with your measuring tape and select one with a little room in the inner circumference size.

JP US Inner Circumference Diameter
(mm) (mm)
1 39.1 12.45
1.5 40.38 12.85
1 40.84 13
2 41.65 13.26
2 41.89 13.33
2.5 42.93 13.67
3 42.94 13.67
4 43.98 14
3 44.21 14.07
5 45.03 14.33
3.5 45.48 14.48
6 46.08 14.67
4 46.76 14.88
7 47.12 15
4.5 48.04 15.29
8 48.17 15.33
9 49.22 15.67
5 49.31 15.7
10 50.27 16
5.5 50.59 16.1
11 51.31 16.33
6 51.87 16.51
12 52.36 16.67
6.5 53.14 16.92
13 53.41 17
7 54.42 17.32
14 54.45 17.33
15 55.5 17.67
7.5 55.7 17.73
16 56.55 18
8 56.97 18.14
17 57.6 18.33
8.5 58.25 18.54
18 58.64 18.67
9 59.53 18.95
19 59.69 19
20 60.74 19.33
9.5 60.8 19.35
21 61.78 19.67