What Does ISO Stand for in Shipping Containers?

July 13, 2018

What Does ISO Stand for in Shipping Containers?

ISO stands for “International Organization for Standardization” and shipping containers that are “ISO shipping containers” have their dimensions regulated by this organization. These dimensional regulations allow these ISO containers to use their amount of space as efficiently as possible no matter what kind of transport they are loaded on. It helps to make transportation of the containers easy, which makes loading and unloading faster, which, of course, everyone loves.

What are ISO Container Sizes and ISO Container Dimensions?

ISO container sizes range from 20 feet all the way to 56 feet, with the most common container sizes being the 20 foot and 40 foot sized containers. ISO container dimensions mostly measure out at 8 feet wide, however, there are a few that measure more than this. These container dimensions fall into two ranges; The letters “C”, “D”, “E”, and “F” identify those ISO containers that are greater than 8 feet, but less than 8.2 feet. ISO Containers that are larger than that 8.2 foot mark are identified by the letters “L”, “M”, “N”, and “P”. ISO container heights measure 8 feet 6 inches, but are also available in several other heights, from 4 feet all the way to 9 feet 6 inches. ISO containers that measure 9 feet 6 inches tall are called “extended height” or “high cube” containers. 4 feet and 4 feet 6 inches tall containers might be (but are not always) called “half height” containers. For reference, here’s a list of the standard ISO container sizes, and dimensions.

Standard ISO Container Sizes


  • 20 foot
  • 24 foot
  • 28 foot
  • 40 foot
  • 44 foot
  • 45 foot
  • 46 foot
  • 53 foot
  • 56 foot

Standard Internal ISO Container Dimensions for Most Common Containers (20 foot, 40 foot, 40 foot High Cube, and 45 foot High Cube)


  • 8 foot 6 inches
  • 9 foot 6 inches


  • 8 foot

Where did ISO begin?

The International Organization for Standardization began in 1946 when representatives from 25 different countries met in London at the Institute of Civil Engineers and decided to make a new international organization whose mission it would be ‘to facilitate the international coordination and unification of industrial standards’. And on February 23, 1947, this new organization -- called ISO -- officially began doing just that.

Quick Fun Fact: Because 'International Organization for Standardization' would have had different acronyms in different languages, such as IOS in English, OIN in French, etc., ISO founders agreed on a short form of the organization’s name -- “ISO”. They derived it from the Greek “isos”, meaning equal. So no matter what country or language you are in, ISO is always ISO.

A Breakdown of ISO Container Types and Codes

The standard identification of intermodal shipping containers is “ISO 6346:1995”. This identification system is used to give each container a unique marking. The code can be broken into three parts; an ISO 6346 (BIC) code, a size and type code, and optional markings. As you can see in the image below.

diagram of numbers on a shipping container and their meaning

Image from: globalspec.com

The ISO 6346 (BIC) code identifies the owner of the container, the product group, and also a unique serial number and check digit that identifies the specific container. The owner code is the first three characters. This specific abbreviation is registered with the Bureau International des Containers et du Transport Intermodal, to make sure that every company has its own unique code. The product group “U” is used for all intermodal containers while “J” is used for equipment attachments and “Z” designates chassis or frames used to carry intermodal containers. The serial number identifies a specific container and it can be cross referenced with the check digit.

graphics of a BIC code for shipping containers

Image from: globalspec.com

So hopefully now you understand what someone means when they say ISO container or when you read “ISO Container” on the internet. It’s just a way that we know the container is standardized and lets us -- and you -- know the container dimensions for the various container sizes available. If you’re looking to purchase a new or used shipping container, get your free quote from Tuff Box today.