a fork lift truck capacity monitor or alerting device informs operators of the weight on the forks and fork height and alerts operators whenever truck speed is above creep with the forks raised above a collapsed height or whenever the forks are raised above a recommended height for a given load . the alerting device includes a control circuit that receives inputs from a speed sensor , a fork height sensor and a weight sensor and reads a memory storing data correlating load weights with maximum recommended fork heights . a truck icon is displayed on a display panel . a plurality of height zone lamps representing the weight of the load on the forks are arranged in a vertical column over the truck icon and selectively illuminated according to the load on the forks . a plurality of lamps represent the height of the forks with the fork height lamps , which include one lamp positioned to represent a lowered position of the forks and a plurality of lamps equal in number to the height zone lamps and placed horizontally opposite therefrom , being selectively illuminated according to the height of the forks . an alarm signal alerts operators whenever the forks are raised above the recommended height for a given load weight , or whenever truck speed exceeds a predetermined maximum speed and the forks are above the collapsed height . the alarm signal may include a combination of an audible signal , a text message , and a flashing lamp .