Wrap a strip of paper, string, or measuring tape around the base of your finger
Mark where the ends meet
Measure the length in millimeters with a ruler
Compare the measurement to a ring size chart
Measure the same finger at the end of the day when it is warm
Measure more than once to confirm accuracy
Make sure the ring can slide over your knuckle comfortably
If between sizes, choose the larger size
Use a ring sizer tool or visit a jeweler for the most accurate result