Ring Size Comparison Chart
Please Note: All equivalents are approximate.
US. & 
Canadian 
Standard
Inside 
Diameter
mm/inches
Inside 
Circumference
mm/inches
Equivalents
BritishFrenchGermanSwiss
1 ½ 12.78/.503 40.2/1.580 C 40 ½ 12¾
2 13.21/.520 41.5/1.634 D 41 ½ 13¼ 2
2 ½ 13.61/.536 42.7/1.684 E 42¾ 13¾ 3
3 14.05/.553 44.0/1.739 F 44 14 4
3 ½ 14.45/.569 45.2/1.788 G 45¼ 14 ½
4 14.86/.585 46.5/1.836 H ½ 46 ½ 15 7
4 ½ 15.27/.601 47.8/1.888 I ½ 47¾ 15¼ 8
5 15.70/.618 49.0/1.941 j ½ 49 15¾ 9
5 ½ 16.10/.634 50.2/1.992 L 50¼ 16
6 16.51/.650 51.5/2.042 M 51 ½ 16 ½ 12
6 ½ 16.92/.666 52.8/2.092 N 52¾ 17 13
7 17.35/.683 54.0/2.146 N ½ 54 17¼ 14
7 ½ 17.63/.699 55.3/2.196 O ½ 55 ½ 17 ½ 15
8 18.19/.716 56.6/2.249 P ½ 56¾ 18 16
8 ½ 18.59/.732 57.8/2.300 Q ½ 58 18 ½ 17
9 18.99/.748 59.1/2.350 R ½ 59¼ 19 18
9 ½ 19.41/.764 60.3/2.400 S ½ 60 ½ 19 ½ 19
10 19.84/.781 61.6/2.463 T ½ 61¾ 20 20
10 ½ 20.24/.797 62.8/2.504 U ½ 62¾ 20¼ 22
11 20.68/.814 64.1/2.567 V ½ 64 ½ 20¾ 23
11 ½ 21.01/.830 66.0/2.608 W ½ 66 21 24
12 21.41/.846 67.3/2.658 Y 67¼ 21 ½ 25