An apparatus for determining the weight of a payload in a bucket of a machine where the bucket is attached to a chassis of the machine by a linkage. The apparatus comprises an energy storage device for storing potential energy of the bucket, payload, and linkage when the bucket is moved from a first suspended position to a second suspended position. A mechanism provides physical data corresponding to a physical change in the energy storage device caused by storage of the potential energy and a processor calculates the weight of the payload using the physical data.