Wrap a strip of paper, string, or dental floss around the base of the finger
Mark where the ends meet
Measure the length with a ruler in millimeters
Compare the measurement to a ring size chart
Measure the finger at the end of the day
Measure the finger when it is warm
Measure the exact finger you will wear the ring on
Repeat the measurement 2 to 3 times for accuracy
If the measurement is between sizes, choose the larger size
Measure an existing ring by comparing its inner diameter to a ring size chart
Make sure the ring fits over the knuckle comfortably
Avoid measuring when your fingers are cold or swollen