The volumetric weight of a shipment is a calculation that reflects the density of a package. A less dense item generally occupies more volume of space, in comparison to its actual 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.
　

we use The formula to calculate the volumetric weight of your shipment as follows:

length（cm）*width（cm）*height（cm）/5000=Volumetric Weight
　

Eg. if your package weigh 20kg, but the package size is: 50cm long, 50cm wide and 50cm high, The volumetric weight is:

50X50X50/5000=25kg

The volumetic weight is higher than actual weight, so your shipping fee will be calculated by 25kg.