Wrap a strip of paper or a piece of string around the base of your finger
Mark the point where the ends meet
Measure the length with a ruler in millimeters
Compare the measurement to a ring size chart
Measure the same finger at the end of the day
Make sure your finger is at a normal temperature
Measure the exact finger and hand where the ring will be worn
Measure more than once for accuracy
If between sizes, choose the larger size
Use a ring sizer tool for the most accurate result