How to find out your ring size:

1. Use a piece of thread or dental floss and wrap it tightly around the knuckle of the finger you want to wear the ring on.
2. Mark the point where the two ends meet with a pen.
3. Take a ruler with millimeters indicated to measure the string.
4. The indicated number in millimeter is your ring size. For example if it is 5.1 cm your ring size is 51. If you're slightly over 5.2 cm take the next bigger size, which would be 52.

If you're still not sure about your size you can also order a ring sizer for free here Ring Sizer