How to measure the ring circumference: 1 Choose to measure your finger at dusk or at night, because the size of the finger should be the largest during this time. 2 When the hands feel cold, it is not advisable to measure the size of the finger. It should be measured before the hands are warmed up. 3 The width of the ring depends mainly on which finger is worn, and then the exact size is measured. 4 Use a strip of paper or a tape to make a circle around the finger wearing the ring.