A weight sensor may include a weighing platform and a load cell coupled to the platform to sense a weight applied to the platform, the load cell may include a deformable plate with one or more strain gauges arranged to provide an electrical signal representing the weight applied to the platform, and a base supporting the load cell, wherein the deformable plate is movably mounted to the base at only three contact points, the contact points allowing lateral movement of the plate when the plate deforms in response to a weight applied to the platform. The weight sensor makes it possible to monitor the weight and weight shifting of two people sharing the bed. The weight sensor is self-centering when a load is applied off-center to the platform, which is beneficial when used underneath a bed, e.g., under a bed leg or other support member which may not be aligned.
