Ring Size Guide  
 
Diameter USA, Canada UK, Ireland, Australia Japan Switzerland,
(in) (mm) Europe
0.586 14.9 4 H 7  
0.594 15.1 4 1/4 H 1/2   7.75
0.602 15.3 4 1/2 I 8  
0.61 15.5 4 3/4 J   9
0.618 15.7 5 J 1/2 9  
0.626 15.9 5 1/4 K   10
0.634 16.1 5 1/2 K 1/2 10  
0.642 16.3 5 3/4 L   11.75
0.65 16.5 6 L 1/2 11 12.75
0.658 16.7 6 1/4 M 12  
0.666 16.9 6 1/2 M 1/2 13 14
0.674 17.1 6 3/4 N    
0.682 17.3 7 N 1/2 14 15.25
0.69 17.5 7 1/4 O 15  
0.698 17.7 7 1/2 O 1/2   16.5
0.706 17.9 7 3/4 P 16  
0.714 18.1 8 P 1/2   17.75
0.722 18.3 8 1/4 Q 17  
0.73 18.5 8 1/2 Q 1/2 18  
0.738 18.8 8 3/4 R   19
0.746 19.0 9 R 1/2 19  
0.754 19.2 9 1/4 S   20.25
0.762 19.4 9 1/2 S 1/2 20  
0.77 19.6 9 3/4 T 21 21.5
0.778 19.8 10 T 1/2    
0.786 20.0 10 1/4 U 22  
0.794 20.2 10 1/2 U 1/2 23 22.75
0.802 20.4 10 3/4 V    
0.81 20.6 11 V 1/2 24  
0.818 20.8 11 1/4 W   25
0.826 21.0 11 1/2 W 1/2 25  
0.834 21.2 11 3/4 X 26  
0.842 21.4 12 X 1/2   27.5
0.85 21.6 12 1/4 Y 27  
0.858 21.8 12 1/2 Z 28 28.75
0.866 22.0 12 3/4 Z 1/2    
0.874 22.2 13   29  
0.882 22.4 13 1/4 Z1    
0.89 22.6 13 1/2   30  
0.898 22.8 13 3/4 Z2 31  
0.906 23.0 14 Z3    
0.914 23.2 14 1/4   32  
0.922 23.4 14 1/2 Z4 33  
0.93 23.6 14 3/4      
0.938 23.8 15