Option 1
Measure the inside Diameter on a Ring you Already have
If you have a ring that fits on the finger that you would like to wear your new ring on.
Using a ruler lay the ring on top and measure across the inside of the ring from edge to edge, in the centre where red arrows are in example.
Then take that measurement in mm, which is the diameter and using our measurement-conversion chart below you will find your ring size.
SIZE IN THE EXAMPLE IS A Z/13