Scales are all calibrated differently and you can weigh something different on each one. Unless you are weighing on your doctors scale regularly, then don't worry about it. Use your one "official" scale to accurately gauge your weight loss. The flooring can also affect the scale. Doctors are supposed to calibrate their scales often because so many people weigh on them, but many do not. If you want to check your own scale, put an object you know the weight of on the scale (I like to use my hand weights).