If you already have a ring that fits you perfectly, you can use that ring to find your ring size with these simple steps:
  1. Pick an existing ring for your desired finger
  2. Measure the internal diameter of the ring (in mm).
  3. Use the below chart to get your ring size.

Alternatively, if you know your ring size in another format, here is a conversion chart 

 

INTERNAL DIAMETMM)

14.1

14.9

15.7

16.5

17.3

18.1

19.0

19.8

20.6

21.4

22.2

US/CANADARING SIZE

3

4

5

6

7

8

9

1011

12

13

UK/AUSTRALIA RING SIZ

 

F

H

J

L

N

P

R

T

Vv

X

Z

GERMAN RING SIZE

14

15

15 3/4

16 1/2

17 1/4

18

19

20

20 3/4

21 1/4

22