ISO 6346

ISO 6346 is an international standard covering the coding, identification and marking of intermodal (shipping) containers used within containerized intermodal freight transport. The standard establishes a visual identification system for every container that includes a unique serial number (with check digit), the owner, a country code, a size, type and equipment category as well as any operational marks. The standard is managed by the International Container Bureau (BIC).

Example of an ISO 6346 conform container number:

The owner code consists of three capital letters of the Latin alphabet to indicate the owner or principal operator of the container. Such code needs to be registered at the Bureau International des Conteneurs in Paris to ensure uniqueness worldwide.

The equipment category identifier consists of one of the following capital letters of the Latin alphabet:

Under the ISO code, then, only U, J, and Z are in use—the reefer container is identified by means of the size type code.

The serial number consists of 6 numeric digits, assigned by the owner or operator, uniquely identifying the container within that owner/operator's fleet.

The check digit consists of one numeric digit providing a means of validating the recording and transmission accuracies of the owner code and serial number.

To compute the check digit, the letters have to be converted to numbers. This is done in three steps:

An equivalent numerical value is assigned to each letter of the alphabet, beginning with 10 for the letter A (11 and multiples thereof are omitted):

The individual digits of the serial number keep their numeric value.

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