When your shipment is picked up or received by a forwarder for shipping, both the package’s actual weight and volumetric weight are calculated. The higher of the two figures will be used in computing the shipping cost for the particular package. This is the standard being followed by all airlines and freight forwarders.
To illustrate: Let’s say the volumetric divisor as determined by the shipper is 166. The volume of the item in cubic centimeter (cc) (LxWxH) is then divided by 166 in order to come up with the dimensional weight.
It is worth mentioning that if the volume of a package is reduced sufficiently in a way that the density surpasses the cutoff density, the sender loses the motivation to further reduce the box size. After all, there will be no additional benefits in terms of cost that the added reduction will bring because the shipping charge will be determined by the package weight anyway. It can therefore be concluded that there will be motivation only up to the cutoff density; beyond that, there will be no more motivation.
Sometimes, shipping companies provide volumetric weight calculators as part of their website features, based on the company’s chosen volumetric divisor (ours is 166). We already take into consideration the volume weight when using our shipping calculator. All you have to do is to enter the height, length and width/depth of their packages; the volumetric weight is then computed automatically when determining the charges.