The manual states that this thermometer should be calibrated "at time of manufacture". Unfortunately the unit we had was not. According to this thermometer, the room we were in was 77 degrees (when it was more like 66 degrees) and both my wife and I had temperatures under 96 degrees. This was using both ear and forehead tools.I would not recommend this product. From reading other reviews, it seems some are calibrated correctly, but many others are not.