Inner Diameter (mm) |
Inner Circumference (mm) |
US/Canada Sizes |
Australian/British Sizes |
15.7 |
49.3 |
5 |
J 1/2 |
15.9 |
49.9 |
5 1/4 |
K 1/4 |
16.1 |
50.6 |
5 1/2 |
L |
16.3 |
51.2 |
5 3/4 |
L 1/4 |
16.5 |
51.9 |
6 |
M |
16.7 |
52.5 |
6 1/4 |
M 1/2 |
16.9 |
53.2 |
6 1/2 |
N |
17.1 |
53.8 |
6 3/4 |
N 1/2 |
17.3 |
54.4 |
7 |
O |
17.5 |
54.8 |
7 1/4 |
O 1/2 |
17.8 |
55.8 |
7 1/2 |
P |
17.9 |
56.5 |
7 3/4 |
P 1/2 |
18.2 |
57.2 |
8 |
Q |
18.4 |
57.7 |
8 1/4 |
Q 1/2 |
18.5 |
58.2 |
8 1/2 |
Q 3/4 |
18.7 |
58.7 |
8 3/4 |
R 1/4 |
18.9 |
59.3 |
9 |
R 3/4 |
19.2 |
60.4 |
9 1/4 |
S 1/4 |
19.4 |
60.9 |
9 1/2 |
S 3/4 |
19.6 |
61.6 |
9 3/4 |
T 1/4 |
19.8 |
62.3 |
10 |
T 1/2 |
20.0 |
62.9 |
10 1/4 |
U |
20.2 |
63.5 |
10 1/2 |
U 1/2 |
20.4 |
64.2 |
10 3/4 |
V 1/4 |
20.7 |
64.9 |
11 |
V 1/2 |
20.8 |
65.5 |
11 1/4 |
W 1/4 |
21.1 |
66.2 |
11 1/2 |
W 3/4 |
21.2 |
66.7 |
11 3/4 |
X 1/4 |
21.5 |
67.5 |
12 |
Y |
21.7 |
68.1 |
12 1/4 |
Y 1/2 |
21.9 |
68.8 |
12 1/2 |
Z |
22.1 |
69.4 |
12 3/4 |
Z 1/2 |
22.3 |
70.2 |
13 |
Z+1 |
22.7 |
71.3 |
13.5 |
Z+1.5 |
23.1 |
72.5 |
14 |
Z+3 |
23.4 |
73.5 |
14.5 |
Z+4 |
23.8 |
74.8 |
15 |
Z+5 |
24.2 |
76.1 |
15.5 |
Z+6 |
24.6 |
77.4 |
16 |
Z+7 |