On standard ground freight shipments the weight of the shipment is used to determine the transportation cost. As a rule of thumb, we can use the estimate and the projected weight to develop a cost per pound. This will give you an idea of how a change in weight will impact the pricing. On parcel freight, air and ocean shipments the transportation cost is determined by the higher of the "actual weight" or the "dimensional weight" of your shipment. Dimensional weight is calculated based on the amount of space (cubic inches, feet or meters) that your shipment will take up on the truck, airplane or ocean vessel. For example, shipping a 5 cubic foot container filled with feathers is going to be based on the "dimensional weight" whereas the same container filled with "pig iron" is going to be based on the actual weight.