Sizes

Inside Diameter 

Inside Circumference

 US & CA

UK & AU

MM

Inches

MM

Inches

4.5

I 1/2

15.27

0.601

47.97

1.89

5

J 1/2

15.7

0.618

49.32

1.94

5.5

L

16.1

0.634

50.58

1.99

6

M

16.51

0.65

51.87

2.04

6.5

N

16.92

0.666

53.16

2.09

7

O

17.35

0.683

54.51

2.15

7.5

P

17.75

0.699

55.76

2.2

8

Q

18.19

0.716

57.15

2.25

8.5

Q 3/4

18.53

0.729

58.21

2.29

9

R 3/4

18.89

0.748

59.34

2.35

9.5

S 3/4

19.41

0.764

60.98

2.4

10

T 1/2

19.84

0.781

62.33

2.45

10.5

U 1/2

20.2

0.797

63.46

2.5

11

V 1/2

20.68

0.814

64.97

2.56

11.5

W 3/4

21.08

0.83

66.22

2.61

12

Y

21.49

0.846

67.51

2.66

12.5

Z

21.89

0.862

68.77

2.71

13

Z+1

22.4

0.882

70.3

2.77

13.5

Z+2

22.8

0.898

71.6

2.82

14

Z+3

23

0.906

72.3

2.85

14.5

Z+4

23.4

0.922

73.5

2.9

15

Z+5

23.8

0.938

74.8

2.95