The maritime industry highly influences our modern economy. We often overlook the importance of shipping containers and the ships that carry them. They sail through the ocean across the globe to deliver goods and materials necessary for various industries. 

Almost 90% of the goods are shipped through shipping containers, whether a shoe or a raw material design. But do you know what will happen if one ship delivers the wrong product?

This can lead to confusion, financial loss, and a reason for the valid discrepancy. In this blog, we will define the container prefix in container number and its importance in the shipping industry.

What is the container number?

A container number is a special and unique number that an official shipping carrier and all the members associated with the shipping line can identify and trace at any time. 

It is the one feature that separates one container from the other. One can identify the container number at any point in the journey of container transportation.

The container number is usually present at the top right corner of the container, and it can be identified internationally. As far as the container is concerned, it serves as the reference for all commercial and legal objectives.

The role of ISO and BIC

Container numbers were first assigned by the International Shipping Organisation standards (ISO). And every company that owns a container should register with the Bureau International des Containers (BIC). 

Bureau International des Containers (BIC) was founded under the International Chambers of Commerce in 1933 and is a non-profit international organisation. 

Breakdown of the container number

Container Prefix

A container prefix is a four-letter in the container number. The first three letters of the container prefix are owner code, and the 4th letter is detachable equipment unit. But let us understand the whole of the container number.

Container numbers 

To identify each container, a unique alpha-numerical code is used that usually appears on the top-right corner of the container and the sides to quickly identify the containers.

It is an ISO 6346 standard that each country that ships containers follow.

A container number is a combination of 4 letters, six digits, and one check digit. 

  • Three letters – owner code
  • 4th letter – Equipment category identifier
  • Six digits – serial number or registration number
  • 7th digit – Check digit 

The initial three letters of the container number written in capital depict the Owner code. That means anyone who reads the first three letters can determine the owner of the container. But sometimes, containers are given for rent; therefore, the leasing agreement should be shown if questions are raised.

The 4th letter defines the category of the equipment carried in the container, and therefore it is called the equipment category identifier. There are three major categories:

  • U – It denotes the freight container.
  • J – It refers to equipment attached to the container, such as Genset.
  • Z – It signifies the chassis or trailer.

The following six digits are the only numbers defining the asset’s registration number.

The last digit is called the check digit, enclosed within a box to give it particular importance. It is a single digit that helps to verify the accuracy of the previous ten alpha-numerical digits. 

Other essential markings on the shipping containers

Apart from the container prefix in the container number, there are other markings that a shipping container holds. They are 

  • ISO code
  • CSC plate
  • Capacity marking 

ISO code

Containers are used in various countries with different terms in practice. For example, dry van containers are understood as standard shipping containers. Therefore, it is crucial to define the exact type of container. With the help of ISO codes, one can identify and trace the container type and determine the dimensions.

ISO code combines letters, digits, and a sequence of four letters or numbers. The first letter or number depicts the length of the container. The second character defines the height of the container, while the last two characters of the ISO code define the type of container.

Length of the container 

The length of the container can be 20ft, 40ft, 45ft, or 48ft. For each category, ISO has standardised the characters to eradicate confusion. 


Height of the container

We have encountered two different heights of the container. The standard height containers are 8ft 6in, whereas the high cube containers are 9ft 6in. Let’s see the different codes for them.

8 feet 6 inches2
9 feet 6 inches5

Type of container

The sequence’s last two characters define the container type and its characteristics. There are a lot of combinations; let’s see a few of them;

Type of containerCodeCharacteristicsMain code
General purpose container without ventilation GOpening at one or both ends G0
General purpose container with ventilation VMechanical ventilation system, located internally V2
Dry bulk cargo BClosed  B0
Dry bulk cargo BAirtight B1
Refrigerated RMechanically refrigerated R0

CSC plate – The Container Safety Convention 

The Container Safety Convention (CSC) is an internationally recognised standard for the safety of human beings handling shipping equipment. It also provides international safety regulations across the globe. Contracting Parties are nations that have joined the CSC convention, and their governments are referred to as Administrations.

The CSC plate is bolted to the left side of the container and is encrypted with “ CSC Safety Approved”. 

Capacity marking 

The container number, which includes the container prefix, is one of the many codes on shipping containers. Capacity marking has gross weight, tare weight, net weight, and max cargo volume. These features help to identify the uniqueness of the metal box containers.

All these different codes cannot be combined in a single entity; therefore, other standards are defined. We hope you have understood each of them, from the container prefix in the container number, ISO code, and CSC plate to capacity marking.

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