Ring Size Guide

US size ↔ Japan size (Precious Lab) with inner diameter (mm)
US Size Precious Lab Size Inner Diameter (mm)
3 ¼ 5 14.3
3 ½ 14.5
3 ¾ 6 14.7
4 14.9
4 ⅛ 7 15.0
4 ½ 8 15.3
5 9 15.7
5 ⅜ 10 16.0
5 ¾ 11 16.3
6 ¼ 12 16.7
6 ⅝ 13 17.0
7 14 17.3
7 ½ 15 17.7
7 ⅞ 16 18.0
8 ¼ 17 18.3
8 ¾ 18 18.7
9 ⅛ 19 19.0
9 ⅜ 20 19.3
9 ⅞ 21 19.7
10 ¼ 22 20.0
10 ⅝ 23 20.3
11 ⅛ 24 20.7
11 ½ 25 21.0

We size in Japan sizes. For the most accurate fit, measure the inner diameter of a ring that fits well, or use a ring sizer. Quarter US sizes map to the nearest whole Japan size shown above.