What Is a Conex Box? History, Sizes, and What They Cost

What is a conex box? In everyday American usage, a conex box is simply a steel shipping container: the same corrugated boxes you see stacked on ships, trains, and job sites. The word is not a brand or a different product. It is a piece of US military vocabulary that outlived its original program and became a generic term, the way people say a generic word for a product category without thinking about where it came from. If you are shopping for a conex, you are shopping for a shipping container, and everything below applies to both names.

Where the Term Comes From: CONEX and the U.S. Army

CONEX is short for Container Express, a US Army logistics system developed by the Army Transportation Corps. The Army had experimented with rigid reusable shipping boxes in the late 1940s, and the CONEX program entered service in the early 1950s, moving supplies during the Korean War in standardized steel containers that could go from ship to rail to truck without repacking. The system expanded enormously through the Vietnam era, when the Army fielded CONEX containers by the tens of thousands, and it is widely credited as an important step toward the containerized shipping that now moves most of the world's goods. You can dig into this history through the U.S. Army Transportation Museum at Fort Eustis, Virginia.

Original CONEX boxes were smaller than today's containers, but the name stuck to the concept. When commercial ISO containers took over, soldiers, contractors, and eventually the general public kept calling them conex boxes.

What Is a Conex Box Used for Today?

Everything a shipping container is used for, because it is the same object. Common uses as of 2026:

• Secure storage on farms, job sites, and home properties
• Ground-level offices and break rooms
• Workshops and equipment enclosures
• The structural shell for cabins, homes, and other conversions

Conex vs shipping container is a naming question, not a spec question. You may also hear sea can, ISO container, intermodal container, or storage container. Same box. The terms that do change the product are size, height (standard vs high cube), and condition grade.

Conex Box Sizes and Dimensions

Modern conex boxes follow international container standards, so the sizes are fixed and predictable.

The 20 ft and 40 ft sizes cover the vast majority of purchases. See current inventory in our 20 ft containers and 40 ft containers categories.

What Does a Conex Box Cost?

Conex prices are shipping container prices. As of 2026, typical US ranges run from about $1,300 to $2,500 for a used 20 ft in wind and water tight condition, $2,500 to $3,900 for a new one-trip 20 ft, $1,600 to $2,900 for a used 40 ft, and $3,600 to $5,600 for a new 40 ft high cube. Delivery is the hidden variable in most quotes; at AnchorBox, delivery and placement are included free in all 50 US states and every price is published on the product page in our shipping containers catalog, with online checkout by card link or bank wire.

Buying a New vs Used Conex

A one-trip conex was built overseas and shipped once with cargo before sale. It looks close to new and is the right buy for offices, conversions, and anywhere appearance matters. A used conex, graded cargo-worthy or wind and water tight, has years of service behind it, shows dents and surface rust, and costs meaningfully less while still keeping weather out. For plain storage, a graded used shipping container is usually the rational choice. Avoid ungraded as-is units unless you can inspect them yourself, since door and floor repairs often erase the discount. If you want help choosing a grade, call us at (509) 575-1198.

Frequently Asked Questions

Is a conex box the same as a shipping container?

Yes. Conex is an American nickname derived from the Army's Container Express program of the Korean War era. Today it refers to any standard steel shipping container, new or used.

What sizes do conex boxes come in?

The common sizes are 10, 20, and 40 ft, all 8 ft wide, in standard 8 ft 6 in or high cube 9 ft 6 in heights. A 45 ft high cube is also available in many markets.

How much does a used conex box cost in 2026?

Typically around $1,300 to $2,500 for a used 20 ft and $1,600 to $2,900 for a used 40 ft, depending on grade and region. AnchorBox lists exact prices with free delivery and placement included in all 50 US states.