A patient support apparatus includes detectors and a controller operable to automatically update a tare weight for use in determining a true patient weight. The detectors are configured to produce signals indicating a presence or absence of a corresponding removable component. The controller is configured to determine weights of each and every removable component on the patient support apparatus and store each weight in a memory. The controller is further configured to receive the signals produced by the detectors and detect any addition or removal of removable components of the patient support apparatus, update the tare weight, and determine a weight of a patient being supported on the patient support apparatus.