A weighing system for use in retrofitting a pallet handling apparatus to provide weighing functionality. The system comprises a control unit and two fork units. The electronic control unit has a display, an electronic weight calculation controller, and at least one control switch. Each fork unit is for substitution with one fork of the pallet handling apparatus. Each fork unit comprises a rigid frame member having an elongated configuration, a plurality of load cells fixedly connected to the frame member, the load cells being disposed in laterally oriented pairs, and a fork member communicatively connected to the frame and engaging the load cells.