Wrap the strip lengthwise around your finger. Make sure that the strip is not too tight and that the ring fits over your knuckle.
Mark the end of the overlap with a line. If possible, use a thin pen.
Measure the marked distance. The result in millimeters is your ring size.

MEASURE WRIST SIZE YOURSELF

Wrap the strip around your wrist lengthwise. Make sure the strip is not too tight.
Mark the end of the overlap with a line.
Measure the marked distance. The result in centimeters equals your bracelet size.