Circumference (mm)
Europe / ISO

Diameter (mm)

USA / Canada

UK / Australia

Asia

Switzerland

44.2

14.1

3

F

4

4

44.8

14.3

F-1/2

5

5-1/4

45.5

14.5

3-1/2

G

46.1

14.7

G-1/2

6

6-1/2

46.8

14.9

4

H

7

47.4

15.1

H-1/2

7-3/4

48.0

15.3

4-1/2

I

8

48.7

15.5

J

9

49.3

15.7

5

J-1/2

9

50.0

15.9

K

10

50.6

16.1

5-1/2

K-1/2

10

51.2

16.3

L

11-3/4

51.9

16.5

6

L-1/2

11

12-3/4

52.5

16.7

M

12

53.1

16.9

6-1/2

M-1/2

13

14

53.8

17.1

N

54.4

17.3

7

N-1/2

14

15-1/4

55.1

17.5

O

55.7

17.7

7-1/2

O-1/2

15

16-1/2

56.3

17.9

P

57.0

18.1

8

P-1/2

16

17-3/4

57.6

18.3

Q

58.3

18.5

8-1/2

Q-1/2

17

58.9

18.8

R

19

59.5

19.0

9

R-1/2

18

60.2

19.2

S

20-1/4

60.8

19.4

9-1/2

S-1/2

19

61.4

19.6

T

21-1/2

62.1

19.8

10

T-1/2

20

62.7

20.0

U

21

63.4

20.2

10-1/2

U-1/2

22

22-3/4

64.0

20.4

V

64.6

20.6

11

V-1/2

23

65.3

20.8

W

25

65.9

21.0

11-1/2

W-1/2

24

66.6

21.2

X

67.2

21.4

12

X-1/2

25

27-1/2

67.8

21.6

Y

68.5

21.8

12-1/2

Z

26

28-3/4

69.1

22.0

Z-1/2

69.7

22.2

13

27

70.4

22.4

Z + 1

71.0

22.6

13-1/2