Wrap a strip of paper or a piece of string 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
Repeat the measurement 2–3 times for accuracy
Measure at the end of the day when fingers are largest
Make sure the paper or string is snug, not tight
Measure the finger you will wear the ring on
Account for wider rings by choosing a slightly larger size
If between sizes, choose the larger size