This cool wristband is approximately 2" (5.1cm) wide. Measure the length around your wrist, and add exactly 1 1/2" (3.8cm) to that size. This is the size that you order. So if your wrist is 6" (15.2cm), please order the 7 1/2" (19.1cm) band. Please note: MOST ADULTS WILL NOT FIT IN WRISTBAND SIZES BELOW 7".