These are the standard dimensions of boxes, pallets and freight containers that are used in shipping.
Some of the shippers custom make their boxes and pallets so that it fits in the freight containers to the maximum and optimises the space in the container.
Freight containers have a standard dimension as set out the International Standard Organisation.
In the European trades, a certain type of pallet size 1200×800×144 mm is used. When combined with the new container type called the Pallet Wide (PW) Container, built to accommodate these special pallets, a European customer can load 30 Euro-pallets in a 40’ Pallet-Wide-Container in comparison to 25 in a 40’ standard container.