Wrap a strip of paper or a soft measuring tape around the base of the finger
Mark where the ends meet
Measure the length in millimeters
Compare the measurement to a ring size chart
Measure the finger at the end of the day
Measure when fingers are warm, not cold
Measure the exact finger the ring will be worn on
Check the ring size using an existing ring that fits well
Measure the inside diameter of the ring
Compare the diameter to a ring size chart
Repeat the measurement for accuracy
Consider the width of the ring band
If between sizes, choose the larger size