Wrap a flexible tape measure completely around your wrist where the bracelet is to be worn. The reading on the tape will indicate your bracelet size. In order to have some movement and flexibility, add about one centimeter (or four tenths of an inch) to that measurement.
Example : 15,5cm (6.1") + 1cm (0.4") = Size S
Size S = 16,5cm / 6.5"
Size M = 17,5cm / 6.8"
Size L = 18,5cm / 7.2" Size XL = 19,5cm / 7.6"