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 reefers (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 3 TEUs of containers are available for every TEU of 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 maximum 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.
The tank container market represents a niche with its separate logistics and operations. They are double-hulled and insulated with a carrying capacity of around 25,000 liters. There are two sub-markets for tank containers. The first is food grade where tank containers can be used to carry consumable liquids, particularly oils, alcohol, and juices. The second concerns chemicals for industrial use. Between each usage, a tank container needs to be thoroughly cleaned. Unlike regular containers and reefers, tank containers are usually not stored at a container terminal for a long duration as they require to be picked up as soon as possible and brought to a specialized depot.