Option 1: Measure one of your rings
Option two. Finding Your Ring Size Using Paper or String
Cut a strip of paper or a piece of string. The paper strip should be approximately 1/2" wide, and 5" long.
Wrap the paper or string around the finger to be sized. Slide the paper or string up to the knuckle, as the ring must be sized large enough to able to slip off and on, over the knuckle.
Use a pen to mark the string or paper where the long end overlaps.
Measure the mark from the end of the length of paper or string with a ruler.Use the metric side for more accurate sizing.