TEU: Twenty Foot Equivalent Unit
The two most common international standardised container types are twenty and forty foot. A twenty foot unit measures about 6 meters, a forty foot about 12 meters (external dimensions). Depending on whether the ship loads twenty or forty foot containers (or a combination of the two), the number of containers held on board the ship will differ. As to express the capacity of a container ship in a uniform manner, the number of containers that the ship can load is converted into a number of containers of the smallest size, i.e. those that are twenty feet in length.
A forty foot container is regarded as two twenty foot containers or 2 TEU (sometimes referred to as FEU, Forty Foot Equivalent Unit). To calculate how many TEU a container is, just divide the actual length in feet by twenty. In terms of costs, reference is often made to costs per TEU, which means that these costs will double for 40 foot containers.
TEU is also used to indicate the nominal capacity of container ships or container terminals and in statistics regarding container transit in ports.