Every scale you weigh on may weigh you something different. Scales are calibrated differently and the flooring they are can effect it too. Scale should be on a hard level surface. You should pick one scale as your "official" scale and don't worry about the rest. To most accurately gauge your weight loss, weigh same clothes, same time, same everything. I like in the morning before eating or drinking anything and after going to the bathroom. If you weighed yourself every hour all day long the scale would constantly go up and down because of water weight. As long as the scale has a mostly downward trend, you are doing well.