For packing purposes, substances other than those of classes 1, 2, 5.2, 6.2 and 7, and other than self-reactive substances of class 4.1, are assigned to three packing groups in accordance with the degree of danger they present:

Packing Group I – High danger
Packing Group II – Medium danger
Packing Group III – Low danger

If applicable the relevant packing group⁹⁷ is shown in column 5 of the DG L. The criteria for determining the packing group is found in the classification section of each applicable class in IMDG Part 2.

Note, articles are not assigned to packing groups, rather the specific packaging performance test is set out in the applicable packing instruction.

Packing groups are not assigned to articles or to explosives of Class 1 or gases of Class 2. Organic peroxides of Class 5.2 and self-reactive substances of Class 4.1 do not have packing groups but are allocated a Type ( A to G) according to degree of danger⁹¹.

Rules for determining packing groups and types are found in IMDG Chapter 2 in the section containing classification rules for each of the classes.

Where packing groups are allocated to a UN Number, that packing group is indicated in column 5 of the Dangerous Goods List.

The packing group of N.O.S. mixtures and solutions will depend on the degree of danger as determined by the classification tests carried out by the shipper/product supplier. Some N.O.S entries are listed under more than one packing group because the composition of mixtures is variable, and may have a greater or lesser concentration of the dangerous substance in the mixture. The multiple entries make sense because the packing group affects the type of packaging, and may change the packaging requirements.

Where a packing group exists, it must be included on the cargo booking and in the shipper’s declaration/ transport document, but does not need to be displayed on packages.

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⁹⁷ IMDG Code, 2022 Edition Amendment 41-22, Sections 2.0.1.3