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 the finger when it is warm
Measure the exact finger the ring will be worn on
Repeat the measurement a few times for accuracy
Use a ring sizer if available
If between sizes, choose the larger size