Circumference (in mm)
UK Size
US / Canada
37.54
HAS
1/2
38.86
B
1
40.15
C 1 1/2
41.5 D 2
42.76
E 2 1/2
44.14 F 3
45.11 G 3 3/8
46.02 H 3 3/4
47.25 I 4 1/4
48.38 I 4 5/8
49.64 K 5 1/8
50.58 L 5 1/2
51.87 M 6
53.16 N 6 1/2
54.51 O 7
55.76 P 7 1/2
57.15
Q 8
58.47 R 8 5/8
60 S 9 1/8
61.29 T 9 5/8
62.89 U 10 1/4
63.84
V
10 5/8
65.22
W 11 1/8
66.54
X 11 5/8
67.51
Y 12
68.77
Z
12 1/2