International Ring Size Conversion Chart
by The Official International Ring Size Guide
| 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 |
– |
– |
– |
– |
– |
|
