America
Circumference (mm)
Diameter (mm)
Europe and Australia
Asia
Switzerland
3
44.2
14.1
F
4
4
44.8
14.3
F½
5
5½
3½
45.5
14.5
G
46.1
14.7
G½
6
6½
4
46.8
14.9
H
7
47.4
15.1
H½
7¼
4½
48
15.3
I
8
48.7
15.5
J
9
5
49.3
15.7
J½
9
50
15.9
K
10
5½
50.6
16.1
K½
10
51.2
16.3
L
11¼
6
51.9
16.5
L½
11
12¼
52.5
16.7
M
12
6½
53.1
16.9
M½
13
14
53.8
17.1
N
7
54.4
17.3
N½
14
15¼
55.1
17.5
O
7½
55.7
17.7
O½
15
16½
56.3
17.9
P
8
57
18.1
P½
16
17¾
57.6
18.3
Q
8½
58.3
18.5
Q½
17
58.9
18.8
R
19
9
59.5
19
R½
18
60.2
19.2
S
20¼
9½
60.8
19.4
S½
19
61.4
19.6
T
21½
10
62.1
19.8
T½
20
62.7
20
U
21
10½
63.4
20.2
U½
22
22¾
64
20.4
V
11
64.6
20.6
V½
23
65.3
20.8
W
25
11½
65.9
21
W½
24
66.6
21.2
X
12
67.2
21.4
X½
25
27½
67.8
21.6
Y
12½
68.5
21.8
Z
26
28¾
69.1
22
Z½
13
69.7
22.2
27