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Markings On A Shipping Container – What Do They Mean?

Sea Freight

Markings On A Shipping Container – What Do They Mean?

If you’re in the business of importing and exporting, the shipping container is one of the most – if not, the most – important pieces of equipment you’ll use. It’s what gets your product from point of origin to point of destination and has been doing the job since containers were first used by horse-drawn carts in the late 18th century.

The markings on your containers are critical at every stage in the supply chain, as they’re responsible for signaling to various parties the important information they need to keep your goods secure.

If you’re looking to find out more about the meanings of markings on shipping containers, you’ve come to the right place. Below, we’ll consider everything ranging from container numbers and ISO Codes to classifications and cubes.

What are the ISO identification markings on a container?

The ISO is the International Standards Organisation (ISO), an international body based in Geneva formed out of several standards organisations that promote different commercial and industrial standards across the world.

The ISO developed a range of codes, referred to as ISO standard 6346 (or simply ISO 6346), which are used to mark shipping containers transported throughout domestic and international supply chains. They’re commonly referred to as ISO identification markings.

ISO identification markings on a container pursuant to ISO 6346 are the unique numbers used to identify the owner of a container and other integral information such as its weight, payload and type.

Each of the following ISO markings must be displayed on both ends, both sides and at the top of a container:

  • Container numbers (consisting of owner codes, equipment categories, serial numbers and check digits);
  • Country codes; and
  • Size and type codes
Markings On A Shipping Container – What Do They Mean?


Container numbers

The container number is the primary marking on the door of the container. It’s a sequence consisting of seven numbers and four letters.

An example of a container number could be ‘HBXU 3005342 ’.

This code comprises of the:

  • Owner code: three letters, being HBX in the above example. Owner codes are unique to the individual owner and are registered with the Bureau of International Containers, known as the Bureau International des Containers et du Transport Intermodal (BIC) in French.
  • Equipment category: consists of one letter. In the above example, this is “U”, signalling a freight container. Some of the other codes include “Z” for trailers and “J” for detachable container-related equipment.
  • Serial number: consists of six numbers, being 300542 in the above example.
  • Check digit: one number after the serial number.  This number is critical because it’s used to determine if the container number sequence is a valid sequence or not.

Freight operators, shipping terminals and others in the supply chain are able to instantly verify container numbers through using the BIC Container Check Digital Calculator available online.

This is because that singular check digit is carefully arrived to using an algorithm that both involves the owner code and serial number.

If you aren’t aware of who the owner is of any particular container, you can perform a BIC Code Search to identify them using the BIC Code Lookup Tool.

Although, note that the owner of the container may not be the person or business operating it. They could have leased the container to another operator (which is common in modern freight shipping) and this won’t be captured by the Lookup Tool.

Size and type codes (sometimes called the ISO Code)

Each container is also given a unique ‘size and type code’ to avoid further ambiguity.

The first character of the code signals the length of the container. The second represents the width and height, whilst the third and fourth character indicates the actual kind of container.

A general 20-foot container may, for example, be marked ‘22G1’ for its size and type code. This indicates to parties in the supply chain that the container:

  • is 20 feet long;
  • is 8 feet, 6 inches high; and
  • has a tare weight of 2,250 kilograms.

Country code

The Country codes consist of two capital letters as described in ISO 3166 (Codes for the representation of names of countries and their subdivisions).

These codes are designed to indicate the country in which the code is registered. It does not indicate, however, the owner or operator’s nationality.

What other markings are included on a container?

There is a range of other markings that are mandatory to include on shipping containers, which we will outline in detail below.

Container owner or lessor

The shipping container may be marked with the entity of who owns or is operating the container. It may be a shipping line (such as Maersk or ONE) or it might a containing leasing company (like Seaco Global, for example).

Leasing companies may be useful for those shipping lines that need to increase their inventory in the short-term, but don’t wish to expand their assets in the long term.

Maximum gross weight

Containers will also typically be marked with the maximum gross weight that they are able to carry. Different types of containers will contain different maximum gross weights, but shipping lines and also local regulations will sometimes impose a weight limit for containers.

For example, a typical 20-foot container may be able to carry a maximum weight of 25,400 kilograms (about 28 tonnes), but shipping lines can and do impose limitations on this amount.

It is also important to observe local laws if your shipment needs to be transported on roads. In Brisbane, for instance, the maximum loaded weight of a container on roads allowed is 24 tonne, higher limits are possible when using lightweight trucks or applying for special permits.

Classification society label

This label demonstrates to the supply chain that the container has been tested for strength, seaworthiness and cargo worthiness.

Before containers are used to transport cargo, they are tested for these attributes by an approved classification society. The standards are set by the ISO.

Container weight

Containers will be labelled with their empty or tare weight. Typically, this is provided by the container’s manufacturer.

It is a very important container element as it’s used by planners to assess how many containers can actually be loaded onto a ship, this is why an accurate container weight declaration is mandatory. Overloading a ship with too much cargo, exceeding the maximum weight the ship can carry, will inevitably increase the risk of an accident at sea.

Maximum payload

The maximum payload refers to the maximum weight of cargo that can be placed into the container.

A failure to declare the proper payload can lead to a container being transported incorrectly, causing damage to property and potentially to human life.

The payload will be on a bill of lading, but importantly, it does not include the container’s tare weight.


The cube refers to the maximum volume (in cubic capacity) that can be loaded into a shipping container.

As opposed to weight, it’s simply impossible to overpack a container, however, the loader must be sure that all cargo is safe and secure. An incorrect declaration of the maximum volume on a bill of lading could potentially lead to economic loss for an importer or an exporter. This is particularly the case if the cargo is sold by volume.

CSC certification plate

Containers, prior to being shipped, must have a safety approval pursuant to the International Convention for Safe Containers (CSC). This was a treaty adopted by the United Nations and the International Maritime Organisation in 1972 to create uniform safety regulations in global container shipping.

Once a container receives an CSC approval, it will have an approval plate demonstrating to parties in the supply chain that it is adequate to be used in trade. Indeed, it shows that the container has been inspected and is safe for transportation.

The plate will contain all relevant information including technical data and owner details.



Final tip – mandatory operational markings

Other markings you’ll need to include on your containers are operational markings.

These are compulsory to include and are designed to show parties in your supply chain certain warnings about the weight of the container, if overhead electrical danger exists and if your container is higher than 2.6 meters.

Further questions?

If you have any further queries about what any markings on a shipping container mean, please don’t hesitate to contact our expert freight specialists at International Cargo Express.

Our staff have had decades of combined experience handling different types of shipping containers, so are well-placed to answer any questions you may have. Feel free to call us or you can request a quote.

Request A Quote

or call us on 1300 227 461

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