Size (mm)

Diameter (mm)

U.S.A. size

Australian/UK size

48

15.27

4 1/2

I 1/2

49

15.70

5

J 1/2

51

16.10

5 1/2

L

52

16.51

6

M

53

16.92

6 1/2

N

55

17.35

7

O

56

17.75

7 1/2

P

57

18.19

8

Q

58

18.53

8 1/2

Q 1/2

59

18.89

9

R 1/2

61

19.41

9 1/2

S 1/2

62

19.84

10

T 1/2

63

20.20

10 1/2

U 1/2

65

20.68

11

V 1/2

66

21.08

11 1/2

W 1/2

68

21.49

12

Y

69

21.89

12 1/2

Z

70

22.33

13

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