International Ring Size Conversion Chart


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Inside Inside Inside Inside Number
Sizes
Letter
Sizes
Number
Sizes
Number
Sizes
Number
Sizes
Diameter Diameter Circumference Circumference US/Canada British Japanese French Swiss
(inches) (mm) (inches) (mm) Standard Irish Equivalent Equivalent Equivalent
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 B 1    
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 C      
0.514 13.1 1.614 41.0 1 3/4 C 1/2      
0.522 13.3 1.639 41.6 2 D 2 41-1/2 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 E 3 42-3/4 2.75
0.546 13.9 1.714 43.5 2 3/4 E 1/2   43-3/8  
0.554 14.1 1.740 44.2 3 F 4 44 4.00
0.562 14.3 1.765 44.8 3 1/4 F 1/2 5 44-5/8 5.25
0.570 14.5 1.790 45.5 3 1/2 G   45-1/4  
0.578 14.7 1.815 46.1 3 3/4 G 1/2 6 ---- 6.50
0.586 14.9 1.840 46.7 4 7 46-1/2  
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 8 47-3/4  
0.610 15.5 1.915 48.7 4 3/4 J   48-3/4 9.00
0.618 15.7 1.941 49.3 5 J 1/2 9 49  
0.626 15.9 1.966 49.9 5 1/4 K   49-5/8 10.00
0.634 16.1 1.991 50.6 5 1/2 K 1/2 10 50  
0.642 16.3 2.016 51.2 5 3/4 L   50-7/8
11.75
0.650 16.5 2.041 51.8 6 L 1/2 11 51-1/2 12.75
0.658 16.7 2.066 52.5 6 1/4 12 52-1/8  
0.666 16.9 2.091 53.1 6 1/2 M 1/2 13 52-3/4 14.00
0.674 17.1 2.116 53.8 6 3/4 N   53-3/8  
0.682 17.3 2.141 54.4 7 N 1/2 14 ---- 15.25
0.690 17.5 2.167 55.0 7 1/4   54  
0.698 17.7 2.192 55.7 7 1/2 O 1/2 15 54-5/8 16.50
0.706 17.9 2.217 56.3 7 3/4   55-1/4  
0.714 18.1 2.242 56.9 8 P 1/2 16 55-7/8 17.75
0.722 18.3 2.267 57.6 8 1/4   56-1/2  
0.730 18.5 2.292 58.2 8 1/2 Q 1/2 17 57-1/8  
0.738 18.7 2.317 58.9 8 3/4 R   57-3/4 19
0.746 18.9 2.342 59.5 9 R 1/2 18 58-3/8  
0.754 19.2 2.368 60.1 9 1/4 S   59 20.25
0.762 19.4 2.393 60.8 9 1/2 S 1/2 19 59-5/8  
0.770 19.6 2.418 61.4 9 3/4 T   60-7/8 21.5
0.778 19.8 2.443 62.1 10 T 1/2 20 61-1/2  
0.786 20.0 2.468 62.7 10 1/4 U 21 62-1/8  
0.794 20.2 2.493 63.3 10 1/2 U 1/2 22 62-3/4 22.75
0.802 20.4 2.518 64.0 10 3/4 V   63-3/4  
0.810 20.6 2.543 64.6 11 V 1/2 23 64  
0.818 20.8 2.569 65.2 11 1/4 W   64-5/8 25
0.826 21.0 2.594 65.9 11 1/2 W 1/2 24 65-1/4  
0.834 21.2 2.619 66.5 11 3/4 X   65-7/8  
0.842 21.4 2.644 67.2 12 X 1/2 25 ---- 27.50
0.850 21.6 2.669 67.8 12 1/4   66-1/2  
0.858 21.8 2.694 68.4 12 1/2 Z 26 67-3/4 28.75
0.866 22.0 2.719 69.1 12 3/4 Z 1/2   68-3/8  
0.874 22.2 2.744 69.7 13   27 69  
0.882 22.4 2.769 70.3 13 1/4 Z1      
0.890 22.6 2.795 71.0 13 1/2        
0.898 22.8 2.820 71.6 13 3/4 Z2      
0.906 23.0 2.845 72.3 14 Z3      
0.914 23.2 2.870 72.9 14 1/4        
0.922 23.4 2.895 73.5 14 1/2 Z4      
0.930 23.6 2.920 74.2 14 3/4        
0.938 23.8 2.945 74.8 15        
0.946 24.0 2.970 75.4 15 1/4        
0.954 24.2 2.996 76.1 15 1/2        
0.962 24.4 3.021 76.7 15 3/4        
0.970 24.6 3.046 77.4 16        

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