Ring Size Conversion Chart

British
Irish
Australian

USA
Canada 

Japanese 

Swiss 

J

4 3/4

9

J 1/2

5

9

K

5 1/4

10

K 1/2

5 1/2

10

L

5 3/4

11.75

L 1/2

6

11

12.75

M 

6 1/4

12

M 1/2

6 1/2

13

14

N

6 3/4

N 1/2

7

14

15.25

O 

7 1/4

O 1/2

7 1/2

15

16.5

P 

7 3/4

P 1/2

8

16

17.75

Q 

8 1/4

Q 1/2

8 1/2

17

R

8 3/4

19

R 1/2

9

18

S

9 1/4

20.25

S 1/2

9 1/2

19

T

9 3/4

21.5

T 1/2

10

20

U

10 1/4

21

U 1/2

10 1/2

22

22.75

V

10 3/4

V 1/2

11

23

W

11 1/4

25

W 1/2

11 1/2

24

X

11 3/4

X 1/2

12

25

27.5

Y 

12 1/4

Z

12 1/2

26

28.75

Z 1/2

12 3/4

13

27

Z+1

13 1/4

13 1/2

Z+2

13 3/4

Z+3

14

14 1/4

Z+4

14 1/2

Japan

USA

Measured Size (mm)

1

1

C

40.8

2

2

D

41.9

3

2.5

E

42.9

4

3

F

44.0

5

3.5

G

45.0

6

3.5-4

G-H

46.1

7

4-4.5

H-I

47.1

8

4.5-5

I-J

48.2

9

5

J

49.2

10

5.5

K

50.3

11

6

L

51.3

12

6.5

L-M

52.4

13

6.5-7

M-N

53.4

14

7-7.5

N-O

54.5

15

7.5-8

O-P

55.5

16

8

P

56.6

17

8.5

Q

57.6

18

9

R

58.6

19

9.5

S

59.7

20

10

T

60.7

21

10-10.5

T-U

61.8

22

10.5

U

62.8

23

11

V

63.9

24

11.5

W

64.9

25

12

X

66.0

26

12.5

Y

67.0

27

13

Z

68.0