Wrap a strip of paper or string around the base of the finger
Mark where the ends meet
Measure the length in millimeters with a ruler
Compare the measurement to a ring size chart
Use a ring that already fits
Measure the inside diameter of the ring in millimeters
Compare the diameter to a ring size chart
Try the ring on at the end of the day when fingers are largest
Measure the same finger more than once for accuracy
Make sure the ring can slide over the knuckle comfortably
If between sizes, choose the larger size
Use a printable ring sizer if available
Check sizing for the correct hand and finger
Avoid measuring when fingers are cold or swollen