The cost of a shipment can be affected by the amount of space that it occupies on an aircraft or ship, rather than the actual weight. This is the volumetric (or dimensional) weight.
Generally, freight charges are calculated on the actual weight of the goods plus packing (gross weight) but if the goods are a low weight but large in volume then the freight carrier may charge for the amount of space the goods use. In this case an estimated weight is calculated from the length, width and height of a package.
The concept of volumetric weight has been adopted by the transportation industry worldwide as a uniform means of establishing a minimum charge for the cubic space a package occupies.