Corrugated Boxes are 3-Dimensional objects and therefor require three sizes. In the Packaging Industry boxes are always measured as Length x Width x Height (Depth). The arrangement of these three sizes determine where the box will open and ultimately what shape it will take once completed. Due to the high level of accuracy required, box sizes are always given in mm and will correspond to the inner dimensions.
In Shipping, the volumetric weight of a shipment is a calculation that reflects the density of a package. Less dense items generally occupy more volume of space, in comparison to it’s actual weight. The cost of transporting a shipment can be affected by the amount of space that it occupies on an aircraft rather than it's actual weight. Due to the importance of Volumetric Weight rather than acctual size, shipping companies will measure the outer dimensions of a package in cm rather than mm. Volumetric Weight is calculated as Length x Height x Width and divided by 4000 for normal domestic road freight.