Measure your wrist size
S - 16cm (6.3 Inch)
M - 18.5cm (7.3 Inch)
L - 21.5cm (8.4 Inch)
Use a normal tape measurer or a strip of paper just below the wrist bone, where you would normally wear a bracelet. Please accomodate for movement around wrist when choosing the correct size.
If you’re using a strip of paper, you can mark the overlap with a pen, and then measure the length with a normal ruler on a flat surface.