Source: Drewry Shipping Consultants.
The 40 footer, both in its standard and “high cube” form, is the most common container, accounting for 68% of all TEUs, while the 20 footer accounts for 26%. The remaining 16% involves specialized containers such as the reefer (7%). About 90% of the world’s containers are made in China, namely because China is a large exporter of manufactured goods. The total number of containers being used is very difficult to estimate. An approximate figure indicates that there are 3 TEUs of containers available for every TEU of available maritime containership capacity.
The composition of the container fleet is a balancing act between the requirements of “weighting out” and the requirements of “cubing out”, which is related to the nature of what is being carried. Even if higher container units tend to be desirable since they can carry greater quantities of goods, the containerization of commodities, such as grain, indicates that the 20 footer is likely to remain an important intermodal unit. It can carry a full load of 20 tons while larger containers are limited to a maximal load of 28 tons, irrespective of their size. For standard retail goods, the 40-foot high cube is the preferred unit since the load unit will cube out well before reaching its maximum weight.