Manual measurement,due to different individual techniques,1-3cm error is normal,not quality problem.
Note :The size in our store is for Asian,it is 1~3(0.39-1.18inch)size smaller than Europe/US size,we suggest to purchase 1-3(0.39-1.18inch) bigger size than usual.If you are not sure about the size,please let us know your weight,and waist Info ect. So that we an help you to choose the correct