The easiest way is to calculate the diameter of your finger. Take a string or a piece of paper and wrap it around your finger to determine the circumference of your finger. This is best done at the place where your finger is the widest since your ring must be able to slide over this place. multiply this length by 3.14, and voila you have the diameter of your finger.
Everywhere in the world people use different values and systems to indicate a ring size. Look for your finger diameter in this chart. In the same line you will find the corresponding values from the other systems. In our product information we use the diameter and the European system.