The bracelet size recommended is for comfort fit which is adding an extra 2 cm / 0.79" to your wrist circumference measurement.
Measuring your wrist
1) Use a tape measure, or if you do not have one, use a strip of paper, ribbon or cord. Wrap it around your wrist where you would normally wear the bracelet.
2) If you are using a strip of paper, ribbon or cord. Mark the end of the strip and then measure the length against a ruler. This is your wrist size.