There are many different sizes and types of containers in the world today. The two most basic and common are the 20 foot and 40 foot. One 20ft until equals 1 TEU (Twenty Foot Equivalent Unit) and one 40ft until equals 2 TEU. This is important to know as vessels sizes are described based on the maximum number of TEU they can carry.
The standard height for containers is 8’6” but there are variations called 40ft High Cubes that are 9’6” high. The standard width for containers is 8’0”. 45 foot containers are always 9’6” high (diagram bottom left). Overleaf is a list of the new ISO codes in use and the different types of containers.
As container shipping evolved, containers began to be developed for specific cargos or trades. Thus the standard 20 and 40ft units are just the tip of the iceberg when it comes to container types.
This wider range of container types also allowed shipping lines to charge additional premiums based on the container used. For example, a refrigerated (Reefer) container is much more profitable than a container holding only dry cargo.