You can follow the next steps to chose the ring size that fits you most: 

  1. Take a ring that you already have and that fits you perfectly.
  2. Measure the ring's inner diameter.  
  3. In the following table, depending on the measurement obtained, you will find your size and the different equivalences depending on the country.
SIZE T.8 T.10 T.12 T.14 T.16 T.18
DIAMETER (mm) 14.86 15.70 16.51 17.35 18.19 18.89
US & CANADA US 4 US 5 US 6 US 7 US 8 US 9
UK & AUSTRALIA H 1/2 J 1/2 M O Q R 3/4
EU 46 1/2 49 51 1/2 54 56 1/2 59
GERMANY 15 15 3/4 16 1/2 17 1/4 18 19