International Ring Size Guide

Inside Diameter Inside Circumference Sizes
MM Inches MM Inches US & Canada British & Australian French German Japanese Swiss
15.7 0.618 49.32 1.94 5 J 1/2 - 15 3/4 9 -
15.8 0.622 49.64 1.95 5 1/8 K 50 - - 10
15.9 0.626 49.95 1.97 5 1/4 K 1/4 - - - -
16 0.63 50.27 1.98 5 3/8 K 1/2 - - 10 -
16.1 0.634 50.58 1.99 5 1/2 L 51 3/4 16 - 11 3/4
16.3 0.642 51.21 2.02 5 3/4 L 1/4 - - - -
16.41 0.646 51.55 2.03 5 7/8 L 1/2 - - - -
16.51 0.65 51.87 2.04 6 M 52 3/4 16 1/2 12 12 3/4
16.71 0.658 52.5 2.07 6 1/4 M 1/2 - - - -
16.92 0.666 53.16 2.09 6 1/2 N 54 17 13 14
17.13 0.674 53.82 2.12 6 3/4 N 1/2 - - - -
17.35 0.683 54.51 2.15 7 O 55 1/4 17 1/4 14 15 1/4
17.45 0.687 54.82 2.16 7 1/4 O 1/2 - - - -
17.75 0.699 55.76 2.2 7 1/2 P 56 1/2 17 3/4 15 16 1/2
17.97 0.707 56.45 2.22 7 3/4 P 1/2 - - - -
18.19 0.716 57.15 2.25 8 Q 57 3/4 18 16 17 3/4
18.35 0.722 57.65 2.27 8 1/4 Q 1/2 - - - -
18.53 0.729 58.21 2.29 8 1/2 Q 3/4 - 18 1/2 17 -
18.61 0.733 58.47 2.3 8 5/8 R 59 - - 19
18.69 0.736 58.72 2.31 8 3/4 R 1/4 - - - -
18.8 0.74 59.06 2.32 8 7/8 R 1/2 - - - -
18.89 0.748 59.34 2.35 9 R 3/4 - 19 18 -
19.1 0.752 60 2.36 9 1/8 S 60 1/4 - - 20 1/4
19.22 0.757 60.38 2.38 9 1/4 S 1/4 - - - -
19.31 0.76 60.66 2.39 9 3/8 S 1/2 - - - -
19.41 0.764 60.98 2.4 9 1/2 S 3/4 - 19 1/2 19 -
19.51 0.768 61.29 2.41 9 5/8 T 61 1/2 - - 21 1/2
19.62 0.772 61.64 2.43 9 3/4 T 1/4 - - - -
19.84 0.781 62.33 2.45 10 T 1/2 - 20 20 -
20.02 0.788 62.89 2.48 10 1/4 U 62 3/4 - 21 22 3/4
20.2 0.797 63.46 2.5 10 1/2 U 1/2 - 20 1/4 22 -
20.32 0.8 63.84 2.51 10 5/8 V 63 - - 23 3/4
20.44 0.805 64.21 2.53 10 3/4 V 1/4 - - - -
20.68 0.814 64.97 2.56 11 V 1/2 - 20 3/4 23 -
20.76 0.817 65.22 2.57 11 1/8 W 65 - - 25
20.85 0.821 65.5 2.58 11 1/4 W 1/4 - - - -
20.94 0.824 65.78 2.59 11 3/8 W 1/2 - - - -
21.08 0.83 66.22 2.61 11 1/2 W 3/4 - 21 24 -
21.18 0.834 66.54 2.62 11 5/8 X 66 1/4 - - 26 1/4
21.24 0.836 66.73 2.63 11 3/4 X 1/4 - - - -
21.3 0.839 66.92 2.64 11 7/8 X 1/2 - - - -
21.49 0.846 67.51 2.66 12 Y 67 1/2 21 1/4 25 27 1/2
21.69 0.854 68.14 2.68 12 1/4 Y 1/2 - - - -
21.89 0.862 68.77 2.71 12 1/2 Z 68 3/4 21 3/4 26 28 3/4
22.1 0.87 69.43 2.73 12 3/4 Z +1/2 - - - -
22.33 0.879 70.15 2.76 13 Z+1 - 22 27 -
22.6 0.89 71 2.8 13.5 Z+1.5 - - - -