Last week, I called the manufacturer of my scales to ask a few questions. One call I am happy I made!!! Like several blood glucose meters, my scales must be calibrated often, or an innaccurate weight reading will be given. Was totally unaware they need calibrated. The rep I spoke with stepped me thru to calibrate. Mine wouldn't calibrate, so I got to box up and ship to them for an exchange. Thankfully there is a 5 year warranty, and it will take 2-3 weeks to receive the new scales. In saying this, I don't recommend these scales. Why? Being unaware of needing calibration and when not calibrated, they will show a regain (even a large amt) when weight hasn't been regained!! Mine showed a 16.2 lb gain in 14 day's! I flipped out!!! I so miss the old fashioned scales we step on and get 1 reading!!