inner
circumference
 (mm)

diameter
(mm)
Japanese sizes
US sizes
UK sizes
40.8 13 1 1 C
41.9 13  1/3 2 2 D
42.9 13  2/3 3 21/2 E
44 14 4 3 F
45 14  1/3 5 31/2 G
46.1 14  2/3 6 31/2~4 G-H
47.1 15 7 4~41/2 H-I
48.2 15  1/3 8 41/2~5 I-J
49.2 15  2/3 9 5 J
50.3 16 10 51/2 K
51.3 16  1/3 11 6 L
52.4 16  2/3 12 61/2 L-M
53.4 17 13 61/2~7 M-N
54.5 17  1/3 14 7~71/2 N-O
55.5 17  2/3 15 71/2~8 O-P
56.6 18 16 8 P
57.6 18  1/3 17 81/2 Q
58.6 18  2/3 18 9 R
59.7 19 19 91/2 S
60.7 19  1/3 20 10 T
61.8 19  2/3 21 101/2 U
62.8 20 22 101/2 V
63.9 20  1/3 23 11 W
64.9 20  2/3 24 111/2 X
66 21 25 12 Y
66.9 21  1/3 26 121/2 Z
68 21  2/3 27 13  
69.1 22 28 131/2  
70.1 22  1/3 29 14  
71.2 22  2/3 30 141/2  
72.3 23 31 15  
73.3 23  1/3 32 151/2