Europe
ring size

USA

British

Japan

Circumference

in millimeters

Circumference

in inch

42 or 2

1.5

     A

2

13.370

.5263

43 or 3

2.0

B

3

13.689

.5389

44 or 4

2.5

C

4

14.007

.5514

45 or 5

3.0

D

5

14.326

.5640

46 or 6

3.5

E

6

14.644

.5765

47 or 7

4.0

F

7

14.963

.5890

48 or 8

4.5

G

8

15.281

.6141

49 or 9

5.0

H

9

15.600

.6266

50 or 10

5.5

I

10

15.918

.6392

51 or 11

6.0

J

11

16.236

.6617

52 or 12

6.5

K

12

16.554

.6642

53 or 13

7.0

L

13

16.873

.6768

54 or 14

7.5

M

14

17.191

.6893

55 or 15

8.0

N

15

17.509

.7018

56 or 16

8.5

O

16

17.828

.7144

57 or 17

9.0

P

17

18.146

.7269

58 or 18

9.5

Q

18

18.465

.7394

59 or 19

10.0

R

19

18.783

.7520

60 or 20

10.5

S

20

19.101

.7645

61 or 21

11.0

T

21

19.420

.7770

62 or 22

11.5

U

22

19.738

.7896

63 or 23

12.0

V

23

20.056

.8021

64 or 24

12.5

W

24

20.375

.8146

65 or 25

13.0

X

25

20.693

.8272

66 or 26

13.5

Y

26

21.011

.8397

67 or 27

14.0

Z

27

21.330

.8522

68 or 28

14.5

Z+1