A method for estimating the effective volumetric capacity of a truck body is provided. The method includes the step of establishing a side-to-side profile of a generic load model. A front-to-rear profile of the generic load model is also established. Load plateau lines having predetermined dimensions are established in the front-to-rear and side-to-side profiles and the height of the plateau lines are determined. A top profile of the generic load is then created and the shape of the load plateau is adjusted into a closed curve shape. The front, rear and side load lines below the final outer boundary of the load plateau are then contoured into a generally conical shaped surface. The final three-dimensional generic load model is formed by where this generally conical shaped surface intersects the sides walls, front and floor of the truck body. The volume of the final three-dimensional generic load model can then be calculated.