Carrying Capacity of Containers (in cubic feet)

The initial container sizes were the "20 footer" and the "40 footer" agreed upon in the 1960s and became an ISO standard. Initially, the "20 footer" was the most widely used container. However, as containerization became widely adopted in the 1990s, shippers switched to larger container sizes, notably the "40 footer". Larger sizes confer economies of scale in loading, handling and unloading, which are preferred for long distance shipping as well as by customers shipping large batches of containerized commodities. The same ship capacity would take in theory twice as much time to load or unload if 20 footers where used instead of 40 footers. There is thus an evident rationale to use the largest container size possible. Consequently, the 20 footer is gradually been phased out. "Hi cube" containers have also been put in use, notably since they do not require different handling equipment or road clearance. They are one feet higher (9'6") than the standard 8'6" height and a 40 footer hi-cube container provides about 12% more carrying capacity than its standard counterpart. Most North American double stack rail corridors can handle two stacked hi-cube containers, creating an additional multiplying effect in terms of total capacity per rail car. The 53 feet hi-cube container is solely a domestic container used in the United States between rail and trucking.

The European Union is trying to implement a new container labeled the European Intermodal Load Unit (EILU), which would have a length of 45 feet and a width of 8.5 feet. The rationale behind this standard is that it would allow two of the standard European pallets to be placed in containers side by side as existing containers are based on North American pallet dimensions. While the new dimensions would still meet clearances for road and rail transport in Europe as well as abroad, the EILU is being strongly opposed by maritime shipping lines, because they have huge investments in current equipment and new ships under construction are optimized for current ISO container sizes. Because containers have useful lives of about 15 years, intermodal carriers are reluctant to adopt any new standard because of prior commitments in capital investment in modal and intermodal infrastructures.