What’s a container number? 

A container number is a unique alpha-numeric combination of seven numbers and four letters used for identifying containers internationally. It’s assigned to each container by the classification agency International Standards Organization (ISO) through the Bureau International des Containers (BIC). The BIC uses the ISO 6346 standard when assigning the container numbers.

Container numbers provide valuable information about the cargo, transportation, ownership, and condition of the shipping container. Read on to find out how.

Understanding the container number format

Each container marking plays a significant role in transportation. Markings are important for monitoring and general safety of a container. Let’s have a look at each of these container markings individually to get an idea of what they mean.

Owner prefix code 

The first three capital letters of the container number are known as the Owner Prefix Code. It helps identify the container owner. For example, ‘MAEU’ is the owner prefix code for Maersk. Each prefix code must be unique and registered with the BIC to avoid duplicates. For your understanding, we’ve taken ‘BIC’ as the owner code in our above-illustrated example.

Equipment category identifier 

This is the letter that appears right after the Owner Prefix Code. In our example, it’s ‘U’ which stands for freight containers. Other categories are: J – detachable freight containers related equipment; and Z – trailers and chassis.

Together with the owner code, the category can be grouped under one term, known as an alpha prefix.

Serial number 

Next, comes the serial or registration number. It’s a six-digit number decided by the owner of the container. In our example, ‘123456’ is the serial number of the container. A container owner can have up to 1 million serial number combinations!

Check digit 

The last number of the container number- that’s placed out of the rest of the numbers on the right side is called the check digit. In our example, we’ve used ‘7’ as the check digit. It’s always boxed to ensure it stands out from the rest of the number. Although it seems insignificant, it is of vital importance. It allows operators, terminals, depots and other parties in the supply chain to automatically validate the container number.

If you type the BIC code and the 6-digit serial number into the BIC Check Digit Calculator, it’ll display the check digit which validates the container.

ISO Code

The ISO code is usually located below the container number. It’s a sequence of four letters or digits. It provides information about the container type and dimensions. The first character of ISO code represents the length of the unit and the second character represents the width or height. The third and fourth characters determine the type of container it is.

Let’s take an example of an ISO code ‘45G1’. Here, ‘45’ indicates that it’s a 45ft high cube container. ‘G1’ indicates that it’s a general-purpose container. Depending on the country, a container is labelled as Dry Van (DV), General Purpose (GP or G1), Standard (SD), or Dry Container (DC).

If you see a container, you’ll notice that there are many other markings on it apart from the container number. Read on to find out what these markings mean and what they tell you about the container and the cargo being transported.

What are mandatory operational markings?

Operational markings are mostly found on the doors of the containers. But the container number and the size and type codes are also displayed on both sides for crane operators, transporters, authorities and forklift operators.

These mandatory operational markings on containers give all the necessary information needed for the movement of containers. These also include visual warnings.

Let’s understand what these markings mean with reference to the image above.

• • Maximum gross and tare mass: Gross weight indicates the maximum weight of a loaded container, while tare weight indicates the weight of the empty container. In this case, 32,500kg or 71,650 lbs is the maximum gross weight and 3,660 or 8,070 lbs is the tare mass.
  • Net weight: Also called payload, the net weight is gross weight minus tare weight. It’s the maximum weight that can be loaded in the container. In the example, 28,840 or 63,580 lbs is the net weight.
  • Maximum cargo volume: This marking is labelled as CU. CAP, which stands for ‘cubic capacity’.It indicated the maximum volume of cargo that can be loaded in the container. It’s provided because cargo is usually measured in volume before it’s measured in weight. In the example above, the cargo volume of the container is 67.6 cubic metres or 2,386 cubic feet.

Now that you have an idea of all the markings displayed on a container, let’s take a look at some other markings.

• • Height marks for containers: Containers higher than 2.6m or 8ft 6 incheshave a height warning. Height marks are displayed in two places on the container. One, on the top edge of each side and the other below the identification number of the container.
  • Logos: Some containers, as you can see from the image above, also have different logos. It can be a manufacturer’s logo, an owner’s logo or a repair recommendation logo.

Although ISO doesn’t provide any standards for the quality of operational markings, it’s recommended that these markings last the entire life of the container.

Now that you have an idea of the various markings, let’s come back to the container number and see how it helps in keeping track of containers.