International Ring Sizing

Use the table below for converting from US to Standard International sizes.
Please note that diameters and circumferences are internal dimensions.

Find Your Ring Size Here

USA Britain Japan Europe Diameter Diameter Circumference Circumference
Canada Australia India, China Swiss Internal (inches) Internal (mm) Internal (inches) Internal (mm)
0       0.458 11.6 1.438 36.5
1/4       0.466 11.8 1.463 37.2
1/2 A     0.474 12 1.488 37.8
3/4 A 1/2     0.482 12.2 1.513 38.4
1 B 1   0.49 12.4 1.539 39.1
1 1/4 B 1/2     0.498 12.6 1.564 39.7
1 1/2 C     0.506 12.9 1.589 40.4
1 3/4 C 1/2     0.51413.1 1.614 41
2 D 2 1.5 0.522 13.3 1.639 41.6
2 1/4 D 1/2     0.53 13.5 1.664 42.3
2 1/2 E 3 2.75 0.538 13.7 1.689 42.9
2 3/4 E 1/2     0.546 13.9 1.714 43.5
3 F 4 4 0.554 14.1 1.74 44.2
3 1/4 F 1/2 5 5.25 0.562 14.3 1.765 44.8
3 1/2 G     0.57 14.5 1.79 45.5
3 3/4 G 1/2 6 6.5 0.578 14.7 1.815 46.1
4 7   0.586 14.9 1.84 46.7
4 1/4 H 1/2   7.75 0.594 15.1 1.865 47.4
4 1/2 8   0.602 15.3 1.89 48
4 3/4 J   9 0.61 15.5 1.915 48.7
5 J 1/2 9   0.618 15.7 1.941 49.3
5 1/4 K   10 0.626 15.9 1.966 49.9
5 1/2 K 1/2 10   0.634 16.1 1.991 50.6
5 3/4 L   11.75 0.642 16.3 2.016 51.2
6 L 1/2 11 12.75 0.65 16.5 2.041 51.8
6 1/4 12   0.658 16.7 2.066 52.5
6 1/2 M 1/2 13 14 0.666 16.9 2.091 53.1
6 3/4 N     0.674 17.1 2.116 53.8
7 N 1/2 14 15.25 0.682 17.3 2.141 54.4
7 1/4     0.69 17.5 2.167 55
7 1/2 O 1/2 15 16.5 0.698 17.7 2.192 55.7
7 3/4     0.706 17.9 2.217 56.3
8 P 1/2 16 17.75 0.714 18.1 2.242 56.9
8 1/4     0.722 18.3 2.267 57.6
8 1/2 Q 1/2 17   0.73 18.5 2.292 58.2
8 3/4 R   19 0.738 18.7 2.317 58.9
9 R 1/2 18   0.746 18.9 2.342 59.5
9 1/4 S   20.25 0.754 19.2 2.368 60.1
9 1/2 S 1/2 19   0.762 19.4 2.393 60.8
9 3/4 T   21.5 0.77 19.6 2.418 61.4
10 T 1/2 20   0.778 19.8 2.443 62.1
10 1/4U21   0.786 20 2.468 62.7
10 1/2 U 1/2 22 22.75 0.794 20.2 2.493 63.3
10 3/4 V     0.802 20.4 2.518 64
11 V 1/2 23   0.81 20.6 2.543 64.6
11 1/4 W   25 0.818 20.8 2.569 65.2
11 1/2 W 1/2 24   0.826 21 2.594 65.9
11 3/4 X     0.834 21.2 2.619 66.5
12 X 1/2 25 27.5 0.842 21.4 2.644 67.2
12 1/4     0.85 21.6 2.669 67.8
12 1/2 Z 26 28.75 0.858 21.8 2.694 68.4
12 3/4 Z 1/2     0.866 22 2.719 69.1
13  27 0.87422.2 2.744 69.7
13 1/4 Z1     0.882 22.4 2.769 70.3
13 1/2       0.89 22.6 2.795 71
13 3/4 Z2     0.898 22.8 2.82 71.6
14 Z3     0.906 23 2.845 72.3
14 1/4       0.914 23.2 2.87 72.9
14 1/2 Z4     0.922 23.4 2.895 73.5
14 3/4       0.93 23.6 2.92 74.2
15 Z5      0.938 23.8 2.945 74.8
15 1/4       0.946 24 2.97 75.4
15 1/2       0.954 24.2 2.996 76.1
15 3/4       0.96224.43.021 76.7
16       0.97 24.6 3.046 77.4