The value of a shipment can be affected by the amount of space it occupies during distribution, rather than the actual weight which is known as volumetric (or dimensional) weight.

The volumetric or dimensional weight is calculated and compared with the actual weight of the shipment to ascertain which is greater; the higher weight is used to calculate the shipment cost.  

For Air Express and Air Cargo , Road Express booking under Priority product, if any dimension of the parcel exceeds 110cms then 2 times the weight (Gross or Volumetric, whichever is more) is directly charged to the customer as the railway authorities charge the same.