ISO 6346

The ISO 6346:1995 international standard defines:

  • a container identification system
  • a coding system for container size and type
  • operational marks
  • physical presentation of marks on the container

Identification System

ISO 6346 establishes a visual identification system for every shipping container that includes an owner code, equipment category identifier, serial number and check digit.

It is this unique 11 digit shipping container number which is required for container tracking.

ISO 6346 container number

Known as "ISO shipping containers", compliant containers are today manufactured according to internationally recognised standards. This means that they can be handled, transported and tracked with ease and efficiency.

Containers that do not follow the ISO 6346 standard are generally transport provider owned containers. The absence of a compliant identification code can cause problems for both other transport providers and container terminals to correctly identify the equipment and properly deliver the cargo.

Owner Code

The owner code consists of three Latin letter characters that identify the owner or principal operator of the container.

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Equipment Category Identifier

There are 3 possible equipment category identifiers:

  • U for all freight containers
  • J for detachable freight container-related equipment
  • Z for trailers and chassis

Serial Number

The serial number consists of 6 numeric digits, assigned by the owner or operator, uniquely identifying the container.

Check Digit

The check digit consists of one numeric digit providing a means of validating the accuracy of the owner code, equipment category identifier and serial number.

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Size and Type Codes

The size and type code is comprised of the following elements:

  1. One character, representing the length
  2. One character, representing the width and height
  3. Two characters indicating the type of the container

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Operational Marks

Mandatory operational marks include the maximum gross and tare weight of the container. These are ISO 668 rated mass limits, not legal limits.

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ISO 6346 specifies four preferred layouts for the placement of the shipping container number components, and the size and type code.

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