The Belt Scale (conveyor belt weighing system) is an industrial device used for the continuous measurement of the mass flow rate of bulk materials as they move along a conveyor belt, without interrupting or disturbing the conveying process, and is installed on a section of fixed idler rollers beneath the belt. The unit consists of a rectangular metal frame supporting a set of idler rollers, Four axle assemblies connected to the main frame , and load cells mounted at the frame's connection points to the conveyor support structure to measure the instantaneous load weight on the belt.

Operation is based on the simultaneous measurement of the material weight over a defined section of the belt and the belt's travel speed: as the material-laden belt passes over the rollers of this frame, the weight force is transmitted to the load cells and converted into a proportional electrical signal. The control system combines the instantaneous weight data (from the load cells) with the belt speed data (from speed sensor) to calculate the instantaneous and cumulative mass flow rate of the material passing through. Due to its ability to provide accurate, uninterrupted flow measurement at high capacities, this system is widely used in industries such as cement, mining, steel, and mineral processing for monitoring and controlling material inventory on transfer lines.