TEU (Twenty foot equivalent unit)

A unit based on an ISO container of 20 foot length (6.10 m) to provide a standardised measure of containers of various capacities and for describing the capacity of container ships or terminals.
One 20 Foot ISO container equals 1 TEU.
One 40 Foot ISO container equals 2 TEU
One container with a length between 20 and 40 foot equals 1.50 TEU
One container with a length of more than 40 foot equals 2.25 TEU.