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Key takeaways
  • A CONEX box is a shipping container developed in 1952 by the US military to efficiently move and store supplies, such as food and weapons, during the Korean War. 
  • CONEX box dimensions are 8 feet and 6 inches (2.59 metres) long, 6 feet 3 inches (1.91 metres) wide and 6 feet 10 and a half inches (2.08 metres) tall.
  • A CONEX box costs between US$1,500 to US$6,000 (around £1,157 to £4,630), depending on its size, age, condition, distance travelled and whether you buy or lease it.

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What is a CONEX box?   |   CONEX box dimensions   |   How much is a CONEX box?

CONEX box graphic

 

What is a CONEX box?

A CONEX box, also known as a Container Express, is a shipping container developed in 1952 by the US military during the Korean War. The military created CONEXs to efficiently move and store supplies, such as food and weapons, in Korea and later in Vietnam. Robust enough to withstand harsh conditions, CONEX boxes inspired the International Organization for Standardization (ISO)-recognised 20-ft and 40-ft shipping containers used in international trade today. 

 

CONEX box dimensions 

CONEX box dimensions are:

  • Length: 8 feet and 6 inches (2.59 metres)
  • Width: 6 feet 3 inches (1.91 metres)
  • Height: 6 feet 10 and a half inches (2.08 metres)

It can usually carry up to 9,000 pounds (4,082 kilograms) and features double doors on one end and lifting rings on each top corner.

In addition, there are "half-size" versions measuring 6 feet 3 inches (1.91 metres) long, 4 feet 3 inches (1.30 m) wide and 6 feet 10 and a half inches (2.10 m) tall. Depending on specific design capabilities, both versions can generally be stacked three high. 

Shipping container icon pin

CONEX vs shipping container 

CONEX boxes are a specific type of 1950s shipping container with US military origins. In contrast, a shipping container generally refers to modern 20-ft and 40-ft sized ISO boxes that move and store cargo worldwide. 
 
CONEX boxes inspired the development of today's globally standardised containers, but there are key differences between the two: 

Origins and purpose
  • CONEX boxes: one of the earliest standardised containers. The US military developed them in the 1950s for the secure and fast transport of military supplies.
  • Shipping containers: designed for international shipping, supporting seamless movement across multimodal transport, such as planes, trucks, and ships. 
Standardisation 
  • CONEX boxes: primarily for military logistics, without strict global compatibility requirements. 
  • Shipping containers: ISO-standardised, enabling universal compatibility. 
Size 
  • CONEX boxes: smaller, around 8 feet 6 inches long, optimised for military needs in restricted or remote areas. 
  • Shipping containers: larger, typically 20-ft or 40-ft long, for domestic and overseas cargo transport. 
Design focus 
  • CONEX boxes: durability, quick deployment and stackability in rugged environments. 
  • Shipping containers: bigger and can carry heavier loads, designed for long-term use, weather resistance and modifications. 
In summary 
  • CONEX boxes: military-specific containers from the 1950s created for secure, quick deployment and storage of supplies in challenging conditions. 
  • Shipping containers: ISO-standardised 20-ft and 40-ft containers widely used today for seamless compatibility across global shipping networks. 

What does CONEX stand for? 

CONEX is a portmanteau of Container Express (CON+EX). The US military coined the phrase in 1952 to describe specially developed shipping containers that quickly transport supplies. Container (CON) describes its ability to store weapons, food, medical equipment and other military supplies, and Express (EX) describes its swift and efficient movement.

 

A stack of colourful shipping containers

How much is a CONEX box? 

How much a military-issued 1950s CONEX box sells for can reach several thousand dollars. However, they are extremely rare and not widely available to the public. Unlike modern 20-ft or 40-ft ISO shipping containers, the US military phased out their production decades ago.  

When they do appear for sale—typically through military surplus dealers, collectors or auction sites like eBay—prices vary significantly based on age, location and historical significance. Factors such as structural integrity, rust levels and the quality of any refurbishment also play a role.

Given their scarcity, potential buyers must remain patient and vigilant, regularly checking specialised military surplus forums or niche dealer sites for updates. 

 

CONEX or CONNEX? 

The correct term is "CONEX", not "CONNEX" as some people occasionally misspell it. It is derived from the full name "Container Express" and refers explicitly to cargo containers developed, produced and named by the US military for the quick and secure transport of supplies. 

Learn more about international shipping

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International shipping refers to the process of transporting items, such as personal effects or commercial cargo, from one country to another.

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Visit this page to learn about transhipment and how it differs from direct shipment.

Shipping container dimensions

A 40-ft shipping container is 40ft (12.19m) long, 8ft (2.44m) wide and 8ft 6in (2.51m) tall, while a 20-ft container is 20ft (6.1m), 8ft (2.44m) and 8ft 6in (2.51m).

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