If you wish to calibrate your scale, please follow the steps below; 1. Place the scale on a hard and level surface. 2. Briefly step on and off of the scale so that "0.0" is displayed on the scale. 3. The scale is ready for use! *If the scale does not turn on, please make sure you are stepping on it with enough force as it requires at least 10 lbs (4.5 kgs) to turn on.