Shipping Container Sizes Are Standardized

Shipping container sizes were selected through a long process of standardization that lasted from the mid-1950s to 1970. To the early shipping tycoons standardization meant the possibility of intermodal shipping within secure containers from manufacturer to seller anywhere in the world. Container sizes that are standardized saves money and time in the shipping process.

Initially, two U.S. companies led the way in defining standard sizes for intermodal containerization, Sea-Land (formerly Pan Atlantic) and Matson. Sea-Land, the company of legendary entrepreneur, Malcom McLean, operated initially from Newark and other eastern ports throughout the Northern Atlantic. Matson’s routes were from west coast U.S. ports to Hawaii initially. In the early 1960s both companies competed in the burgeoning Japanese market.

In the early 1950s McLean came up with a ship to truck plan that would require shipping container sizes to be standard. Because of Interstate Commerce Commission regulation McLean could not own both trucking and shipping businesses at the time, but his knowledge of the trucking industry helped him to establish relationships with the trucking companies on the east coast so that he could dictate size standards for containers carried by his ships and the trucking industry found it expeditious to respond accordingly. McLean standardized shipping container around a 35’L x 8’W x 8 ½’H steel box, which McLean found optimal from both the standpoint of the merchandise he was carrying, the ships he was converting from World War II retired stock, and the dimensions needed for truck and rail road beds.

Meanwhile, Matson had a little different set of needs for standardized box sizes in its shipping business between California and Hawaii. Matson did sophisticated (for the time) operations research, sending data on their actual shipments through an early IBM computer, to determine that a 20 foot container would work best for the company’s needs. A container over 25 feet would waste space on the average shipment, while a container of less than 20 feet would waste cost more to handle and would not hold as much.

In 1961 the American Standards Association (ASA) got into the act and urged standards around lengths of 10 feet, 20 feet, 30 feet and 40 feet, but without any participation of the two largest shippers, Sea-Land (then called Pan-Atlantic) and Matson. A few years later the International Standards Organization (ISO) deliberated the issue of standardizing shipping container sizes. The ISO was particularly influenced by the ASA standard, and the needs of European railroads and the same dimensions were approved as the ASA standard initially.

Eventually an expanded family of shipping container was adopted by the ISO. There are now five standard lengths including: 20 ft (6.1m), 40 ft (12.2m), 45 ft (13.7m), 48 ft (14.6m), and 53 ft (16.2m). The most popular length within the U.S. containerized shipping industry is the 48 foot unit.

Shipping container sizes are not exact. Heights can range from 8 feet to 9 ½ feet with 8 ½ feet being most common. The width of shipping containers is standardized at 8 feet.