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| Diameter（mm） |
Circumference（mm） |
Japan |
US |
UK |
| 13.0 |
40.8 |
1 |
1 |
B |
| 13.4 |
41.9 |
2 |
2 |
D |
| 13.7 |
42.9 |
3 |
2 1/2 |
E |
| 14.0 |
44.0 |
4 |
3 |
F |
| 14.4 |
45.0 |
5 |
3 1/2 |
G 1/4 |
| 14.7 |
46.1 |
6 |
3 3/4 |
H |
| 15.0 |
47.1 |
7 |
4 |
H 1/2 |
| 15.4 |
48.2 |
8 |
4 1/2 |
I 1/2 |
| 15.7 |
49.2 |
9 |
5 |
J 1/2 |
| 16.0 |
50.3 |
10 |
5 3/8 |
K 1/2 |
| 16.4 |
51.3 |
11 |
5 1/2 |
L |
| 16.7 |
52.4 |
12 |
5 7/8 |
L 1/2 |
| 17.0 |
53.4 |
13 |
6 1/2 |
N |
| 17.4 |
54.5 |
14 |
7 |
O |
| 17.7 |
55.5 |
15 |
7 1/2 |
P |
| 18.0 |
56.5 |
16 |
7 3/4 |
P 1/2 |
| 18.4 |
57.6 |
17 |
8 1/4 |
Q 1/2 |
| 18.7 |
58.6 |
18 |
8 3/4 |
R 1/4 |
| 19.0 |
59.7 |
19 |
9 |
R 3/4 |
| 19.4 |
60.7 |
20 |
9 1/8 |
S |
| 19.7 |
61.8 |
21 |
9 1/2 |
S 3/4 |
| 20.0 |
62.8 |
22 |
10 1/4 |
U |
| 20.4 |
63.9 |
23 |
10 5/8 |
V |
| 20.7 |
64.9 |
24 |
11 |
V 1/2 |
| 21.0 |
66.0 |
25 |
11 1/2 |
W 3/4 |
| 21.4 |
67.0 |
26 |
11 7/8 |
X 1/2 |
| 21.7 |
68.0 |
27 |
12 1/4 |
Y 1/2 |
| 22.0 |
69.1 |
28 |
12 1/2 |
Z |
| 22.4 |
70.2 |
29 |
13 |
Z +1 |
