Step 1: Take a piece of non-stretchable string, ribbon, thread, or a thin strip of paper. Wrap it comfortably around your ring finger, close to the knuckle.

Step 2: With a pen, carefully mark the spot where the string overlaps. For accuracy, make the marks small.

Step 3: Unwrap your marked length. With a ruler, measure it in millimeters. Find your measurement below.