What is an Overpack?

An overpack is a term used in the transportation of hazardous materials or dangerous goods to refer to a large container or packaging that encloses one or more smaller packages

Essentially, it serves as an additional layer of packaging designed to provide protection, containment, and ease of handling during transit.

Here are key points about overpacks:


The primary purpose of an overpack is to consolidate smaller packages of hazardous materials into a single larger unit for easier handling, storage, and transportation.

Size and Construction

Overpacks come in various sizes and designs, ranging from simple boxes, drums, large “pallet cartons (Gaylords) or shrink wrapped pallets to specialized containers specifically designed for hazardous materials such as thermal control units.

Labelling and Marking

ALL individual packages within an overpack must be fully prepared, marked and labeled as if travelling on their own. Unless all markings from all internal packages are visible, Overpacks must be labeled and marked in compliance with applicable regulations, including proper identification of the hazardous materials contained within, as well as any relevant hazard warnings, handling instructions, or regulatory markings.


Overpacks must comply with regulatory requirements established by international organizations such as the International Air Transport Association (IATA), the International Maritime Organization (IMO), and national authorities like the Department of Transportation (DOT) in the United States.


When hazardous materials are packaged in an Overpack, the outer packaging(s) need to be declared on any hazmat shipping papers that are created as well as identifying the inner cartons, drums etc.

Overall, overpacks play a crucial role in the safe and compliant transportation of hazardous materials, providing for efficient handling and logistics operations. Proper labeling, marking, and documentation are essential to ensure that overpacks meet regulatory requirements and maintain the integrity of the hazardous materials during transit.