Please place the scales on a hard flat surface. Refrain from using on carpet Try to stand in the middle place to avoid slip. Stand on the scale in good balance to avoid failure of lock and incorrect illustration No heavy knock on the weighing scale and keep it away from water After moving the position please weigh it several times to get the correct results after automatically calibrate. This body scale is just for family daily use and should not be used as medical usage. You should consult a professional doctor when undertaking any diet or exercise program.