Same steel box, many names
Conex Box & Other Container Names
The industry has accumulated a pile of names for the same corrugated box. Conex box descends from the US military’s “Container Express” program of the 1950s and remains everyday American for any container. Sea can is the Canadian favourite. ISO container, intermodal container, dry van, shipping container, cargo container — all point at the same ISO 668 steel box.
Where each name comes from
Conex / Connex — from the US military’s Container Express program of the early 1950s, which shipped supplies to Korea in rigid steel boxes a decade before the ISO standard existed. The name outlived the program; today it means any 20 or 40 ft box, especially in American construction and storage. Sea can / C-can — Canadian usage for a container that arrived by sea and stayed. Dry van / GP (general purpose) — carrier jargon distinguishing the standard enclosed box from reefer, open top and other specials. Intermodal container — the formal term, describing what the box does: move between ship, rail and road without repacking. One-trip container — a unit that made a single loaded voyage from the factory; the closest thing to “new” on the resale market.
Which name to use when
Booking freight: say “20 ft GP” or “40 HC” — carriers think in size plus type. Buying for storage in the US: search “conex box” alongside “shipping container”; sellers list under both. In Canada: “sea can”. In standards and contracts: “intermodal container” or the ISO 6346 code itself.
Whatever the name, the dimensions are the ones on our chart — a conex box is a 20 ft or 40 ft ISO container.
Frequently asked questions
What size is a conex box?
Conex is just American slang for a shipping container, so the common sizes apply: 20 ft (6.06 × 2.44 × 2.59 m) and 40 ft (12.19 × 2.44 × 2.59 m), plus high cube variants.
Why is it called a conex box?
From “Container Express” — the US military logistics program of the early 1950s that pioneered rigid reusable shipping boxes during the Korean War. The name stuck to the ISO containers that replaced them.
Is a sea can the same as a shipping container?
Yes — “sea can” is the common Canadian term for a standard ISO shipping container.