Standards and certification
ISO 668
ISO 668 is the international standard that classifies series 1 freight containers by their external dimensions. It sets the matching ratings, which include maximum gross mass, and gives minimum internal and door opening sizes for some container types. It covers containers meant for intercontinental traffic.
Why it matters
ISO 668 is why a 20-foot box from one maker fits the same trucks, chassis and ships as a box from another. Portable storage companies rely on it when they buy used containers, match them to trailers and plan delivery. A common mistake is to treat ISO 668 as the full container specification. It summarizes outside sizes and ratings. The detailed internal dimensions come from the ISO 1496 series. Another mistake is to assume every storage unit follows it. Many mobile storage units, offices and domestic trailers are built to other sizes. Ask the seller whether a unit is an ISO series 1 container or a different design before you plan stacking, lifting or shipping.
Read: Shipping container sizes and dimensions for rental fleets
Definition source: iso.org
Related terms
ISO 1496
ISO 1496 is a series of international standards for the specification and testing of series 1 freight containers. Part 1 covers general cargo containers for general purposes, including totally enclosed boxes and some vented or open top types. Other parts cover tank, thermal, dry bulk and platform containers.
ISO 6346
ISO 6346 is the international standard for coding, identification and marking of freight containers. It defines the container identification system, with a way to check that an ID was written correctly. It also defines size and type codes and the operational marks shown on the container.
ISO container
An ISO container is a freight container built to the ISO series 1 standards, such as ISO 668 for classification and dimensions and ISO 1496 for specification and testing. The standards let boxes fit the same ships, trucks and handling gear worldwide.
external dimensions
External dimensions are the length, width and height of a container measured on the outside. ISO 668 classifies series 1 freight containers by external dimensions. A standard 20-foot container is about 20 feet long, 8 feet wide and 8 feet 6 inches tall outside.
maximum gross weight
Maximum gross weight is the most a container may weigh when loaded, including its own tare weight and the cargo. In ISO 668, ratings include the gross mass of the container. Carrier listings often show 30,480 kg for 20-foot and 40-foot dry containers.
twenty-foot equivalent unit (TEU)
A twenty-foot equivalent unit is a general unit of cargo capacity based on a 20-foot-long intermodal container. It is mostly used for container ships and ports. A 20-foot container counts as one TEU, and a 40-foot container counts as two TEU.
For the industry
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