The ISO container standard was first published in 1968.
The original document was ISO/R 668:1968, titled “Dimensions and Ratings of Freight Containers.” It established a common framework for Series 1 freight containers, helping standardize the dimensions and ratings needed for intercontinental transport. Uniform external sizes were crucial because containers had to transfer efficiently among ships, railways, road vehicles, cranes, and port equipment.
ISO 668 has since been revised through successive editions. Later versions formalized classifications, external dimensions, ratings, and, where applicable, minimum internal and door-opening dimensions. The standard works alongside other container standards, including ISO 1496, which is the authoritative series for many container strength and testing requirements.
A common source of confusion is the distinction between the original 1968 ISO recommendation and later numbered editions. ISO/R 668 was the first publication in the series; later editions appeared in 1973, 1979, 1988, 1995, 2013, and 2020. The 1968 date therefore refers to the origin of the ISO 668 container-dimension standard, not to the year of the current edition.