STEP 1: Measure your wrist with a flexible measuring tape just below the wrist bone as shown in the picture below. Mark the number at the point where the tap meets the zero point.
STEP 2: If you are using a plain strip of paper or a piece of string, mark your size with a pen or pencil and measure the length with a regular ruler. That's your wrist size. To ensure the bracelet fits comfortably, add 1.5 cm. You can then add or subtract centimetres according to your fit preference.
 
 INCH CM
7" 17,78
8" 20,32
9" 22,86