| Inside diameter |
Inside circumference |
Sizes |
| (in) |
(mm) |
(in) |
(mm) |
United States
and Canada |
United Kingdom,
Ireland,
and Australia |
Japan,
China |
Switzerland |
| 0.458 |
11.63 |
1.44 |
36.5 |
0 |
|
|
|
| 0.466 |
11.84 |
1.46 |
37.2 |
¼ |
|
|
|
| 0.474 |
12.04 |
1.49 |
37.8 |
½ |
A |
|
|
| 0.482 |
12.24 |
1.51 |
38.5 |
¾ |
A½ |
|
|
| 0.49 |
12.45 |
1.54 |
39.1 |
1 |
B |
1 |
|
| 0.498 |
12.65 |
1.56 |
39.7 |
1¼ |
B½ |
|
|
| 0.506 |
12.85 |
1.59 |
40.4 |
1½ |
C |
|
|
| 0.514 |
13.06 |
1.61 |
41.0 |
1¾ |
C½ |
|
|
| 0.522 |
13.26 |
1.64 |
41.7 |
2 |
D |
2 |
1.5 |
| 0.53 |
13.46 |
1.67 |
42.3 |
2¼ |
D½ |
|
|
| 0.538 |
13.67 |
1.69 |
42.9 |
2½ |
E |
3 |
2.75 |
| 0.546 |
13.87 |
1.72 |
43.6 |
2¾ |
E½ |
|
|
| 0.554 |
14.07 |
1.74 |
44.2 |
3 |
F |
4 |
4 |
| 0.562 |
14.27 |
1.77 |
44.8 |
3¼ |
F½ |
5 |
5.25 |
| 0.57 |
14.48 |
1.79 |
45.5 |
3½ |
G |
|
|
| 0.578 |
14.68 |
1.82 |
46.1 |
3¾ |
G½ |
6 |
6.5 |
| 0.586 |
14.88 |
1.84 |
46.8 |
4 |
H |
7 |
|
| 0.594 |
15.09 |
1.87 |
47.4 |
4¼ |
H½ |
|
7.75 |
| 0.602 |
15.29 |
1.89 |
48.0 |
4½ |
I |
8 |
|
| 0.61 |
15.49 |
1.92 |
48.7 |
4¾ |
J |
|
9 |
| 0.618 |
15.70 |
1.94 |
49.3 |
5 |
J½ |
9 |
|
| 0.626 |
15.90 |
1.97 |
50.0 |
5¼ |
K |
|
10 |
| 0.634 |
16.10 |
1.99 |
50.6 |
5½ |
K½ |
10 |
|
| 0.642 |
16.31 |
2.02 |
51.2 |
5¾ |
L |
|
11.75 |
| 0.65 |
16.51 |
2.04 |
51.9 |
6 |
L½ |
11 |
12.75 |
| 0.658 |
16.71 |
2.07 |
52.5 |
6¼ |
M |
12 |
|
| 0.666 |
16.92 |
2.09 |
53.1 |
6½ |
M½ |
13 |
14 |
| 0.674 |
17.12 |
2.12 |
53.8 |
6¾ |
N |
|
|
| 0.682 |
17.32 |
2.14 |
54.4 |
7 |
N½ |
14 |
15.25 |
| 0.69 |
17.53 |
2.17 |
55.1 |
7¼ |
O |
|
|
| 0.698 |
17.73 |
2.19 |
55.7 |
7½ |
O½ |
15 |
16.5 |
| 0.706 |
17.93 |
2.22 |
56.3 |
7¾ |
P |
|
|
| 0.714 |
18.14 |
2.24 |
57.0 |
8 |
P½ |
16 |
17.75 |
| 0.722 |
18.34 |
2.27 |
57.6 |
8¼ |
Q |
|
|
| 0.73 |
18.54 |
2.29 |
58.3 |
8½ |
Q½ |
17 |
|
| 0.738 |
18.75 |
2.32 |
58.9 |
8¾ |
R |
|
19 |
| 0.746 |
18.95 |
2.34 |
59.5 |
9 |
R½ |
18 |
|
| 0.754 |
19.15 |
2.37 |
60.2 |
9¼ |
S |
|
20.25 |
| 0.762 |
19.35 |
2.39 |
60.8 |
9½ |
S½ |
19 |
|
| 0.77 |
19.56 |
2.42 |
61.4 |
9¾ |
T |
|
21.5 |
| 0.778 |
19.76 |
2.44 |
62.1 |
10 |
T½ |
20 |
|
| 0.786 |
19.96 |
2.47 |
62.7 |
10¼ |
U |
21 |
|
| 0.794 |
20.17 |
2.49 |
63.4 |
10½ |
U½ |
22 |
22.75 |
| 0.802 |
20.37 |
2.52 |
64.0 |
10¾ |
V |
|
|
| 0.81 |
20.57 |
2.54 |
64.6 |
11 |
V½ |
23 |
|
| 0.818 |
20.78 |
2.57 |
65.3 |
11¼ |
W |
|
25 |
| 0.826 |
20.98 |
2.59 |
65.9 |
11½ |
W½ |
24 |
|
| 0.834 |
21.18 |
2.62 |
66.6 |
11¾ |
X |
|
|
| 0.842 |
21.39 |
2.65 |
67.2 |
12 |
X½ |
25 |
27.5 |
| 0.85 |
21.59 |
2.67 |
67.8 |
12¼ |
Y |
|
|
| 0.858 |
21.79 |
2.70 |
68.5 |
12½ |
Z |
26 |
28.75 |
| 0.866 |
22.00 |
2.72 |
69.1 |
12¾ |
Z½ |
|
|
| 0.874 |
22.20 |
2.75 |
69.7 |
13 |
|
27 |
|
| 0.882 |
22.40 |
2.77 |
70.4 |
13¼ |
Z1 |
|
|
| 0.89 |
22.61 |
2.80 |
71.0 |
13½ |
|
|
|
| 0.898 |
22.81 |
2.82 |
71.7 |
13¾ |
Z2 |
|
|
| 0.906 |
23.01 |
2.85 |
72.3 |
14 |
Z3 |
|
|
| 0.914 |
23.22 |
2.87 |
72.9 |
14¼ |
|
|
|
| 0.922 |
23.42 |
2.90 |
73.6 |
14½ |
Z4 |
|
|
| 0.93 |
23.62 |
2.92 |
74.2 |
14¾ |
|
|
|
| 0.938 |
23.83 |
2.95 |
74.8 |
15 |
|
|
|
| 0.946 |
24.03 |
2.97 |
75.5 |
15¼ |
|
|
|
| 0.954 |
24.23 |
3.00 |
76.1 |
15½ |
|
|
|
| 0.962 |
24.43 |
3.02 |
76.8 |
15¾ |
|
|
|
| 0.97 |
24.64 |
3.05 |
77.4 |
16 |
|
|
|
|
|
