International Ring Size Conversion Chart

Inside Inside Inside Inside Number Sizes Comfort Fit   Letter Sizes  
Diameter Diameter Circumference Circumference US/Canada  US/Canada British Swiss
(inches) (mm) (inches) (mm) Standard Comfort  Irish  
       

 

      Australian  
                
0.458 11.6 1.438 36.5 0      
0.466 11.8 1.463 37.2 1/4      
0.474 12.0 1.488 37.8 1/2   A   
0.482 12.2 1.513 38.4 3/4   A 1/2   
0.490 12.4 1.539 39.1 1  1/2 B  
0.498 12.6 1.564 39.7 1 1/4   B 1/2   
0.506 12.9 1.589 40.4 1 1/2 1  C   
0.514 13.1 1.614 41.0 1 3/4   C 1/2   
0.522 13.3 1.639 41.6 2 1 1/2  D 1.50
0.530 13.5 1.664 42.3 2 1/4   D 1/2   
0.538 13.7 1.689 42.9 2 1/2 2  E 2.75
0.546 13.9 1.714 43.5 2 3/4    E 1/2  
0.554 14.1 1.740 44.2 3  2 1/2 F 4.00
0.562 14.3 1.765 44.8 3 1/4   F 1/2 5.25
0.570 14.5 1.790 45.5 3 1/2  3 G   
0.578 14.7 1.815 46.1 3 3/4   G 1/2 6.50
0.586 14.9 1.840 46.7 4  3 1/2 H  
0.594 15.1 1.865 47.4 4 1/4   H 1/2  7.75
0.602 15.3 1.890 48.0 4 1/2  4 I  
0.610 15.5 1.915 48.7 4 3/4   J  9.00
0.618 15.7 1.941 49.3 5 4 1/2  J 1/2  
0.626 15.9 1.966 49.9 5 1/4    K 10.00
0.634 16.1 1.991 50.6 5 1/2 5  K 1/2  
0.642 16.3 2.016 51.2 5 3/4   L  11.75
0.650 16.5 2.041 51.8 6 5 1/2  L 1/2 12.75
0.658 16.7 2.066 52.5 6 1/4   M   
0.666 16.9 2.091 53.1 6 1/2  6 M 1/2 14.00
0.674 17.1 2.116 53.8 6 3/4    N  
0.682 17.3 2.141 54.4 7 6 1/2  N 1/2 15.25
0.690 17.5 2.167 55.0 7 1/4    O   
0.698 17.7 2.192 55.7 7 1/2 7  O 1/2 16.50
0.706 17.9 2.217 56.3 7 3/4    P  
0.714 18.1 2.242 56.9 8  7 1/2 P 1/2 17.75
0.722 18.3 2.267 57.6 8 1/4   Q   
0.730 18.5 2.292 58.2 8 1/2 8  Q 1/2  
0.738 18.7 2.317 58.9 8 3/4   R  19
0.746 18.9 2.342 59.5 9 8 1/2  R 1/2  
0.754 19.2 2.368 60.1 9 1/4    S 20.25
0.762 19.4 2.393 60.8 9 1/2  9 S 1/2  
0.770 19.6 2.418 61.4 9 3/4   T  21.5
0.778 19.8 2.443 62.1 10  9 1/2 T 1/2  
0.786 20.0 2.468 62.7 10 1/4   U  
0.794 20.2 2.493 63.3 10 1/2  10 U 1/2 22.75
0.802 20.4 2.518 64.0 10 3/4    V  
0.810 20.6 2.543 64.6 11  10 1/2 V 1/2  
0.818 20.8 2.569 65.2 11 1/4   W  25
0.826 21.0 2.594 65.9 11 1/2  11 W 1/2  
0.834 21.2 2.619 66.5 11 3/4   X   
0.842 21.4 2.644 67.2 12 11 1/2  X 1/2 27.50
0.850 21.6 2.669 67.8 12 1/4    Y   
0.858 21.8 2.694 68.4 12 1/2 12  Z 28.75
0.866 22.0 2.719 69.1 12 3/4    Z 1/2 &nbsp