Abstract: The present invention is directed to a roll-off truck/trailer and a method for weighing the box that is positioned horizontally on the truck/trailer. More specifically, the present invention is directed to a weighing system mounted on a roll-off truck/trailer that has four lifts, two on each side of the truck/trailer, and load cells mounted on the lifts. The method of the present invention involves positioning a box in a horizontal position on the roll-off truck/trailer and lifting the box with load cells that are fixed on the top of lifts mounted on each side to the chasis of the truck/trailer.