Inside diameter

Inside circumference

Sizes

(in)

(mm)

(in)

(mm)

United States
and Canada

United Kingdom,
Ireland,
and Australia

Japan

Switzerland

0.458

11.63

1.44

36.5

0

0.466

11.84

1.46

37.2

1/4

0.474

12.04

1.49

37.8

1/2

A

0.482

12.24

1.51

38.5

3/4

A 1/2

0.49

12.45

1.54

39.1

1

B

1

0.498

12.65

1.56

39.7

1 1/4

B 1/2

0.506

12.85

1.59

40.4

1 1/2

C

0.514

13.06

1.61

41.0

1 3/4

C 1/2

0.522

13.26

1.64

41.7

2

D

2

1.5

0.53

13.46

1.67

42.3

2 1/4

D 1/2

0.538

13.67

1.69

42.9

2 1/2

E

3

2.75

0.546

13.87

1.72

43.6

2 3/4

E 1/2

0.554

14.07

1.74

44.2

3

F

4

4

0.562

14.27

1.77

44.8

3 1/4

F 1/2

5

5.25

0.57

14.48

1.79

45.5

3 1/2

G

0.578

14.68

1.82

46.1

3 3/4

G 1/2

6

6.5

0.586

14.88

1.84

46.8

4

H

7

0.594

15.09

1.87

47.4

4 1/4

H 1/2

7.75

0.602

15.29

1.89

48.0

4 1/2

I

8

0.61

15.49

1.92

48.7

4 3/4

J

9

0.618

15.70

1.94

49.3

5

J 1/2

9

0.626

15.90

1.97

50.0

5 1/4

K

10

0.634

16.10

1.99

50.6

5 1/2

K 1/2

10

0.642

16.31

2.02

51.2

5 3/4

L

11.75

0.65

16.51

2.04

51.9

6

L 1/2

11

12.75

0.658

16.71

2.07

52.5

6 1/4

M

12

0.666

16.92

2.09

53.1

6 1/2

M 1/2

13

14

0.674

17.12

2.12

53.8

6 3/4

N

0.682

17.32

2.14

54.4

7

N 1/2

14

15.25

0.69

17.53

2.17

55.1

7 1/4

O

0.698

17.73

2.19

55.7

7 1/2

O 1/2

15

16.5

0.706

17.93

2.22

56.3

7 3/4

P

0.714

18.14

2.24

57.0

8

P 1/2

16

17.75

0.722

18.34

2.27

57.6

8 1/4

Q

0.73

18.54

2.29

58.3

8 1/2

Q 1/2

17

0.738

18.75

2.32

58.9

8 3/4

R

19

0.746

18.95

2.34

59.5

9

R 1/2

18

0.754

19.15

2.37

60.2

9 1/4

S

20.25

0.762

19.35

2.39

60.8

9 1/2

S 1/2

19

0.77

19.56

2.42

61.4

9 3/4

T

21.5

0.778

19.76

2.44

62.1

10

T 1/2

20

0.786

19.96

2.47

62.7

10 1/4

U

21

0.794

20.17

2.49

63.4

10 1/2

U 1/2

22

22.75

0.802

20.37

2.52

64.0

10 3/4

V

0.81

20.57

2.54

64.6

11

V 1/2

23

0.818

20.78

2.57

65.3

11 1/4

W

25

0.826

20.98

2.59

65.9

11 1/2

W 1/2

24

0.834

21.18

2.62

66.6

11 3/4

X

0.842

21.39

2.65

67.2

12

X 1/2

25

27.5

0.85

21.59

2.67

67.8

12 1/4

Y

0.858

21.79

2.70

68.5

12 1/2

Z

26

28.75

0.866

22.00

2.72

69.1

12 3/4

Z 1/2

0.874

22.20

2.75

69.7

13

27

0.882

22.40

2.77

70.4

13 1/4

Z1

0.89

22.61

2.80

71.0

13 1/2

0.898

22.81

2.82

71.7

13 3/4

Z2

0.906

23.01

2.85

72.3

14

Z3

0.914

23.22

2.87

72.9

14 1/4

0.922

23.42

2.90

73.6

14 1/2

Z4

0.93

23.62

2.92

74.2

14 3/4

0.938

23.83

2.95

74.8

15

0.946

24.03

2.97

75.5

15 1/4

0.954

24.23

3.00

76.1

15 1/2

0.962

24.43

3.02

76.8

15 3/4

0.97

24.64

3.05

77.4

16