Wrap a strip of paper or string around the base of your finger
Mark where the ends meet
Measure the length in millimeters
Compare the measurement to a ring size chart
Measure your finger at the end of the day
Measure more than once for accuracy
Make sure the paper or string is snug, not tight
Measure the same finger on the hand you will wear the ring on
If you are between sizes, choose the larger size
Use a ring sizer tool if available
Check your size with a jeweler for the most accurate fit