US

UK, Australia

Diameter
(mm)

Circumference (mm)

Spain, Italy, Netherlands, Switzerland

3

F

14.05

44.0

4.00

3.25

14.25

44.6

4.50

3.5

14.45

45.2

5.25

3.75

H

14.65

45.9

6.00

4

H 1/2

14.86

46.5

6.50

4.25

I

15.04

47.1

7.00

4.5

I 1/2

15.27

47.8

7.75

4.75

15.53

48.4

8.50

5

K

15.80

49.3

9.25

5.25

15.90

49.6

9.50

5.5

L

16.10

50.3

10.25

5.75

16.30

50.9

11.00

6

M

16.51

51.5

11.50

6.25

M 1/2

16.71

52.2

12.25

6.5

N

16.92

52.8

12.75

6.75

N 1/2

17.13

53.4

13.50

7

O

17.35

54.0

14.00

7.25

O 1/2

17.45

54.7

14.75

7.5

P

17.75

55.3

15.25

7.75

P 1/2

17.97

55.9

16.00

8

Q

18.19

56.6

16.50

8.25

Q 1/2

18.35

57.2

17.25

8.5

18.53

57.8

17.75

8.75

18.69

58.4

18.50

9

18.89

59.1

19.00

9.25

19.22

59.7

19.75

9.5

19.41

60.3

20.25

9.75

19.62

60.9

21.00

10

T 1/2

19.84

61.6

21.50

10.25

U

20.02

62.2

22.25

10.5

U 1/2

20.20

62.8

22.75

10.75

20.44

63.5

23.50

11

V 1/2

20.68

64.1

24.00

11.25

20.85

64.7

24.75

11.5

21.08

65.3

25.25

11.75

21.24

66.0

26.00

12

Y

21.49

66.6

26.50