The Hands-on Method
Step 1: Take a piece of string or a thin piece of paper.
Step 2: Wrap the rope comfortably to the middle of your fingers, neither too tight nor too loose, and mark it with a pen.
Step 3: Stretch the string or strip and use a ruler to measure the length of the mark
Measure an Existing Ring
Step 1: Choose a suitable ring that you or your friend has already worn.
Step 2: Measure the inside diameter of the ring in millimeters (mm).
Step 3: Use the size chart above to find the matching size (in millimeters) for your ring.