The truck drives onto a scale at the disposal facility where an initial weight is recorded (gross weight). The truck then empties the contents of the dumpster. Next, the truck drives onto a second scale that records the weight of the truck and the empty dumpster (tare weight). The difference between the first and second weights (gross – tare) is the weight of the debris in the dumpster. The scales are regulated by state bureaus of weights and measures.