Inside Diameter

Inside Circumference

Sizes

(in)

(mm)

(in)

(mm)

United States

&
Canada

United Kingdom
&

Australia

Italy, Spain, 
Netherlands,
Switzerland

0.458

11.63

1.44

36.5

0

0.466

11.84

1.46

37.2

¼

0.474

12.04

1.49

37.8

½

A

0.482

12.24

1.51

38.5

¾

0.49

12.45

1.54

39.1

1

B

0.498

12.65

1.56

39.7

0.506

12.85

1.59

40.4

C

0.5

0.514

13.06

1.61

41

1

0.522

13.26

1.64

41.7

2

D

1.75

0.53

13.46

1.67

42.3

2.25

0.538

13.67

1.69

42.9

E

3

0.546

13.87

1.72

43.6

3.5

0.554

14.07

1.74

44.2

3

F

4.25

0.562

14.27

1.77

44.8

4.75

0.57

14.48

1.79

45.5

G

5.5

0.578

14.68

1.82

46.1

6

0.586

14.88

1.84

46.8

4

H

6.75

0.594

15.09

1.87

47.4

7.5

0.602

15.29

1.89

48

I

8

0.61

15.49

1.92

48.7

J

8.75

0.618

15.7

1.94

49.3

5

9.25

0.626

15.9

1.97

50

K

10

0.634

16.1

1.99

50.6

10.5

0.642

16.31

2.02

51.2

L

11.25

0.65

16.51

2.04

51.9

6

11.75

0.658

16.71

2.07

52.5

M

12.5

0.666

16.92

2.09

53.1

13.25

0.674

17.12

2.12

53.8

N

13.75

0.682

17.32

2.14

54.4

7

14.5

0.69

17.53

2.17

55.1

O

15

0.698

17.73

2.19

55.7

15.75

0.706

17.93

2.22

56.3

P

16.25

0.714

18.14

2.24

57

8

17

0.722

18.34

2.27

57.6

Q

17.5

0.73

18.54

2.29

58.3

18.25

0.738

18.75

2.32

58.9

R

19

0.746

18.95

2.34

59.5

9

19.5

0.754

19.15

2.37

60.2

S

20.25

0.762

19.35

2.39

60.8

20.75

0.77

19.56

2.42

61.4

T

21.5

0.778

19.76

2.44

62.1

10

22

0.786

19.96

2.47

62.7

10¼

U

22.75

0.794

20.17

2.49

63.4

10½

23.25

0.802

20.37

2.52

64

10¾

V

24

0.81

20.57

2.54

64.6

11

24.75

0.818

20.78

2.57

65.3

11¼

W

25.25

0.826

20.98

2.59

65.9

11½

26

0.834

21.18

2.62

66.6

11¾

X

26.5

0.842

21.39

2.65

67.2

12

27.25

0.85

21.59

2.67

67.8

12¼

Y

27.75

0.858

21.79

2.7

68.5

12½

Z

28.5

0.866

22

2.72

69.1

12¾

29

0.874

22.2

2.75

69.7

13

29.75

0.882

22.4

2.77

70.4

13¼

Z1

30.5

0.89

22.61

2.8

71

13½

31

0.898

22.81

2.82

71.7

13¾

Z2

31.75

0.906

23.01

2.85

72.3

14

Z3

32.25

0.914

23.22

2.87

72.9

14¼

33

0.922

23.42

2.9

73.6

14½

Z4

33.5

0.93

23.62

2.92

74.2

14¾

34.25

0.938

23.83

2.95

74.8

15

34.75

0.946

24.03

2.97

75.5

15¼

35.5

0.954

24.23

3

76.1

15½

36.25

0.962

24.43

3.02

76.8

15¾

36.75

0.97

24.64

3.05

77.4

16

37.5