US / Canada |
UK |
Japan |
Diameter (mm) |
Circumference (mm) |
4 |
H 1/2 |
7 |
14.8mm |
46.5mm |
4 1/2 |
I 1/2 |
8 |
15.2mm |
48mm |
5 |
J 1/2 |
9 |
15.6mm |
49mm |
5 1/2 |
L |
10 |
16mm |
50.5mm |
6 |
M |
12 |
16.4mm |
52mm |
6 1/2 |
N |
13 |
16.8mm |
53mm |
7 |
O |
14 |
17.3mm |
54.5mm |
7 1/2 |
P |
15 |
17.7mm |
55.5mm |
8 |
Q |
16 |
18.1mm |
57mm |
8 1/2 |
Q 1/2 |
17 |
18.5mm |
58mm |
9 |
R 1/2 |
18 |
18.9mm |
59.5mm |
9 1/2 |
S 1/2 |
20 |
19.3mm |
61mm |
10 |
T 1/2 |
21 |
19.7mm |
62mm |
10 1/2 |
U 1/2 |
22 |
20.1mm |
63.5mm |
11 |
V 1/2 |
24 |
20.6mm |
64.5mm |
11 1/2 |
W 1/2 |
25 |
21mm |
66mm |
12 |
Y |
26 |
21.4mm |
67.5mm |
12 1/2 |
Z |
27 |
21.8mm |
68.5mm |
13 |
Z+1 |
28 |
22.2mm |
70mm |
13 1/2 |
Z+2 |
29 |
22.6mm |
71mm |
14 |
Z+3 |
31 |
23mm |
72.5mm |
14 1/2 |
Z+4 |
32 |
23.4mm |
74mm |
15 |
Z+5 |
33 |
23.9mm |
75mm |