How to Measure Ring Size 
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VIDEO 
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 
– 
– 
– 
– 
–