Inside Diameter (mm)

Inside Circumference (mm)

Ring Size UK

11.95

37.54

A

12.18

38.26

A 1/2

12.37

38.86

B

12.60

39.58

B 1/2

12.78

40.15

C

13.00

40.84

C 1/2

13.21

41.50

D

13.41

42.13

D 1/2

13.61

42.76

E

13.83

43.45

E 1/2

14.05

44.14

F

14.15

44.45

F 1/2

14.36

45.11

G

14.56

45.74

G 1/2

14.65

46.02

H

14.86

46.68

H 1/2

15.04

47.25

I

15.27

47.97

I 1/2

15.40

48.38

J

15.70

49.32

J 1/2

15.80

49.64

K

16.00

50.27

K 1/2

16.10

50.58

L

16.41

51.55

L 1/2

16.51

51.87

M

16.71

52.50

M 1/2

16.92

53.16

N

17.13

53.82

N 1/2

17.35

54.51

O

17.45

54.82

O 1/2

17.75

55.76

P

17.97

56.45

P 1/2

18.19

57.15

Q

18.35

57.65

Q 1/2

18.61

58.47

R

18.80

59.06

R 1/2

19.10

60.00

S

19.31

60.66

S 1/2

19.51

61.29

T

19.84

62.33

T 1/2

20.02

62.89

U

20.20

63.46

U 1/2

20.32

63.84

V

20.68

64.97

V 1/2

20.76

65.22

W

20.94

65.78

W 1/2

21.18

66.54

X

21.30

66.92

X 1/2

21.49

67.51

Y

21.69

68.14

Y 1/2

21.89

68.77

Z

22.10

69.43

Z 1/2