Ring Size

Inside diameter Inside circumference Sizes (in) (mm) (in) (mm) United StatesCanada United Kingdom, Ireland, and Australia Japan, China Switzerland 0.458 11.63 1.44 36.5 0       0.466 11.84 1.46 37.2 ¼       0.474 12.04 1.49 37.8 ½ A     0.482 12.24 1.51 38.5 ¾ A½     0.49 12.45 1.54 39.1 1 B 1   0.498 12.65 1.56 39.7 1¼ B½     0.506 12.85 1.59 40.4 1½ C     0.514 13.06 1.61 41.0 1¾ C½     0.522 13.26 1.64 41.7 2 D 2 1.5 0.53 13.46 1.67 42.3 2¼ D½     0.538 13.67 1.69 42.9 2½ E 3 2.75 0.546 13.87 1.72 43.6 2¾ E½     0.554 14.07 1.74 44.2 3 F 4 4 0.562 14.27 1.77 44.8 3¼ F½ 5 5.25 0.57 14.48 1.79 45.5 3½ G     0.578 14.68 1.82 46.1 3¾ G½ 6 6.5 0.586 14.88 1.84 46.8 4 H 7   0.594 15.09 1.87 47.4 4¼ H½   7.75 0.602 15.29 1.89 48.0 4½ I 8   0.61 15.49 1.92 48.7 4¾ J   9 0.618 15.70 1.94 49.3 5 J½ 9   0.626 15.90 1.97 50.0 5¼ K   10 0.634 16.10 1.99 50.6 5½ K½ 10   0.642 16.31 2.02 51.2 5¾ L   11.75 0.65 16.51 2.04 51.9 6 L½ 11 12.75 0.658 16.71 2.07 52.5 6¼ M 12   0.666 16.92 2.09 53.1 6½ M½ 13 14 0.674 17.12 2.12 53.8 6¾ N     0.682 17.32 2.14 54.4 7 N½ 14 15.25 0.69 17.53 2.17 55.1 7¼ O     0.698 17.73 2.19 55.7 7½ O½ 15 16.5 0.706 17.93 2.22 56.3 7¾ P     0.714 18.14 2.24 57.0 8 P½ 16 17.75 0.722 18.34 2.27 57.6 8¼ Q     0.73 18.54 2.29 58.3 8½ Q½ 17   0.738 18.75 2.32 58.9 8¾ R   19 0.746 18.95 2.34 59.5 9 R½ 18   0.754 19.15 2.37 60.2 9¼ S   20.25 0.762 19.35 2.39 60.8 9½ S½ 19   0.77 19.56 2.42 61.4 9¾ T   21.5 0.778 19.76 2.44 62.1 10 T½ 20   0.786 19.96 2.47 62.7 10¼ U 21   0.794 20.17 2.49 63.4 10½ U½ 22 22.75 0.802 20.37 2.52 64.0 10¾ V     0.81 20.57 2.54 64.6 11 V½ 23   0.818 20.78 2.57 65.3 11¼ W   25 0.826 20.98 2.59 65.9 11½ W½ 24   0.834 21.18 2.62 66.6 11¾ X     0.842 21.39 2.65 67.2 12 X½ 25 27.5 0.85 21.59 2.67 67.8 12¼ Y     0.858 21.79 2.70 68.5 12½ Z 26 28.75 0.866 22.00 2.72 69.1 12¾ Z½     0.874 22.20 2.75 69.7 13   27   0.882 22.40 2.77 70.4 13¼ Z1     0.89 22.61 2.80 71.0 13½       0.898 22.81 2.82 71.7 13¾ Z2     0.906 23.01 2.85 72.3 14 Z3     0.914 23.22 2.87 72.9 14¼       0.922 23.42 2.90 73.6 14½ Z4     0.93 23.62 2.92 74.2 14¾       0.938 23.83 2.95 74.8 15       0.946 24.03 2.97 75.5 15¼       0.954 24.23 3.00 76.1 15½       0.962 24.43 3.02 76.8 15¾       0.97 24.64 3.05 77.4 16