International Ring Size Conversion Chart

Inside Diameter  Inside Circumference Sizes
MM Inches MM Inches British & Australian  US & Canada French & Russian German Japanese Swiss
9.91 0.390 31.13 1.22 – 0000 – – – –
10.72 0.442 33.68 1.39 – 00 – – – –
11.53 0.454 36.22 1.43 – 0 – – – –
11.95 0.474 37.54 1.49 A 1/2 – – – –
12.18 0.482 38.26 1.51 A 1/2 3/4 – – – –
12.37 0.487 38.86 1.53 B 1 – – 1 –
12.60 0.496 39.58 1.56 B 1/2 1 1/4 – – – –
12.78 0.503 40.15 1.58 C 1 1/2 – – – –
13.00 0.512 40.84 1.61 C 1/2 1 3/4 – – – –
13.21 0.520 41.50 1.63 D 2 41 1/2 13 1/2 2 1 1/2
13.41 0.528 42.13 1.66 D 1/2 2 1/4 – – – –
13.61 0.536 42.76 1.68 E 2 1/2 42 3/4 13 3/4 3 2 3/4
13.83 0.544 43.45 1.71 E 1/2 2 3/4 – – – –
14.05 0.553 44.14 1.74 F 3 44 14 4 4
14.15 0.557 44.45 1.75 F 1/2 3 1/8 – – – –
14.25 0.561 44.77 1.76 F 3/4 3 1/4 – – – –
14.36 0.565 45.11 1.77 G 3 3/8 45 1/4 – 5 5 1/4
14.45 0.569 45.40 1.79 G 1/4 3 1/2 – 14 1/2 – –
14.56 0.573 45.74 1.80 G 1/2 3 5/8 – – 6 –
14.65 0.577 46.02 1.81 H 3 3/4 46 1/2 – – 6 1/2
14.86 0.585 46.68 1.84 H 1/2 4 – 15 7 –
15.04 0.592 47.25 1.86 I 4 1/4 47 3/4 – – 7 3/4
15.27 0.601 47.97 1.89 I 1/2 4 1/2 – 15 1/4 8 –
15.40 0.606 48.38 1.90 J 4 5/8 49 15 1/2 – 9
15.53 0.611 48.79 1.92 J 1/4 4 3/4 – – – –
15.70 0.618 49.32 1.94 J 1/2 5 – 15 3/4 9 –
15.80 0.622 49.64 1.95 K 5 1/8 50 – – 10
15.90 0.626 49.95 1.97 K 1/4 5 1/4 – – – –
16.00 0.630 50.27 1.98 K 1/2 5 3/8 – – 10 –
16.10 0.634 50.58 1.99 L 5 1/2 51 3/4 16 – 11 3/4
16.30 0.642 51.21 2.02 L 1/4 5 3/4 – – – –
16.41 0.646 51.55 2.03 L 1/2 5 7/8 – – – –
16.51 0.650 51.87 2.04 M 6 52 3/4 16 1/2 12 12 3/4
16.71 0.658 52.50 2.07 M 1/2 6 1/4 – – – –
16.92 0.666 53.16 2.09 N 6 1/2 54 17 13 14
17.13 0.674 53.82 2.12 N 1/2 6 3/4 – – – –
17.35 0.683 54.51 2.15 O 7 55 1/4 17 1/4 14 15 1/4
17.45 0.687 54.82 2.16 O 1/2 7 1/4 – – – –
17.75 0.699 55.76 2.20 P 7 1/2 56 1/2 17 3/4 15 16 1/2
17.97 0.707 56.45 2.22 P 1/2 7 3/4 – – – –
18.19 0.716 57.15 2.25 Q 8 57 3/4 18 16 17 3/4
18.35 0.722 57.65 2.27 Q 1/2 8 1/4 – – – –
18.53 0.729 58.21 2.29 Q 3/4 8 1/2 – 18 1/2 17 –
18.61 0.733 58.47 2.30 R 8 5/8 59 – – 19
18.69 0.736 58.72 2.31 R 1/4 8 3/4 – – – –
18.80 0.740 59.06 2.32 R 1/2 8 7/8 – – – –
18.89 0.748 59.34 2.35 R 3/4 9 – 19 18 –
19.10 0.752 60.00 2.36 S 9 1/8 60 1/4 – – 20 1/4
19.22 0.757 60.38 2.38 S 1/4 9 1/4 – – – –
19.31 0.760 60.66 2.39 S 1/2 9 3/8 – – – –
19.41 0.764 60.98 2.40 S 3/4 9 1/2 – 19 1/2 19 –
19.51 0.768 61.29 2.41 T 9 5/8 61 1/2 – – 21 1/2
19.62 0.772 61.64 2.43 T 1/4 9 3/4 – – – –
19.84 0.781 62.33 2.45 T 1/2 10 – 20 20 –
20.02 0.788 62.89 2.48 U 10 1/4 62 3/4 – 21 22 3/4
20.20 0.797 63.46 2.50 U 1/2 10 1/2 – 20 1/4 22 –
20.32 0.800 63.84 2.51 V 10 5/8 63 – – 23 3/4
20.44 0.805 64.21 2.53 V 1/4 10 3/4 – – – –
20.68 0.814 64.97 2.56 V 1/2 11 – 20 3/4 23 –
20.76 0.817 65.22 2.57 W 11 1/8 65 – – 25
20.85 0.821 65.50 2.58 W 1/4 11 1/4 – – – –
20.94 0.824 65.78 2.59 W 1/2 11 3/8 – – – –
21.08 0.830 66.22 2.61 W 3/4 11 1/2 – 21 24 –
21.18 0.834 66.54 2.62 X 11 5/8 66 1/4 – – 26 1/4
21.24 0.836 66.73 2.63 X 1/4 11 3/4 – – – –
21.30 0.839 66.92 2.64 X 1/2 11 7/8 – – – –
21.49 0.846 67.51 2.66 Y 12 67 1/2 21 1/4 25 27 1/2
21.69 0.854 68.14 2.68 Y 1/2 12 1/4 – – – –
21.89 0.862 68.77 2.71 Z 12 1/2 68 3/4 21 3/4 26 28 3/4
22.10 0.870 69.43 2.73 Z +1/2 12 3/4 – – – –
22.33 0.879 70.15 2.76 Z+1 13 – 22 27 –
22.60 0.890 71.00 2.80 Z+1.5 13.5 – – – –
22.69 0.893 71.28 2.81 Z+2 – – – – –
22.92 0.902 72.00 2.83 Z+2.5 – – – – –
23.06 0.908 72.45 2.85 Z+3 – – – – –
23.24 0.915 73.01 2.87 Z+3.5 – – – – –
23.47 0.924 73.73 2.90 Z+4 – – – – –
23.55 0.927 73.98 2.91 Z+4.5 – – – – –
23.87 0.940 74.99 2.95 Z+5 – – – – –
24.27 0.956 76.25 3.00 Z+6 – – – – –

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