The container seems like a simple box, but in fact it is one of the most "coordinated" objects in global logistics. Its key value is not in metal, but in compatibility — so that the same unit of cargo passes through the sea → port → railway → auto delivery without repacking.
The 2,438 m width is a compromise between capacity and infrastructure.
ISO fixes a single "universal" dimension in width: 2,438 mm.
If you make it wider, the restrictions increase dramatically: not all platforms, terminal openings, road dimensions and routes can withstand the "extra" centimeters. The standard keeps the container in the mass compatibility zone: it can be placed on standard railway platforms and on standard chassis, without turning each shipment into a special project.
The height of 2,591 m is the height that "fits" into the standard dimensions of transportation.
In the ISO family, the base height of the “standard” is 2,591 mm (8'6").
Then the engineering arithmetic begins: the container + chassis/ platform must pass under bridges, overpasses, a contact network and in tunnels. That is why there is a 2,896 mm (9'6") "high cube nearby — but he did not cancel the base size, because high containers are more difficult to "pass" through all corridors without restrictions.
The length is also not accidental: 20 and 40 feet are the mathematics of docking.
ISO 668 is designed so that different lengths are assembled in multiple combinations, and corner castings and twistlocks match when stacked and secured. That is why the 20-foot module (TEU) has become the basic "unit of account" of the container world.
Weight: 30,480 kg is the “limit of the system", not a whim.
The typical ISO maximum for standard containers is 30,480 kg (gross mass).
Important: this is the rating of the container as a product and its marine/terminal processing. But "how much you can carry on the road" depends on the legislation and axial loads in a particular country. In practice, it is often not the container that limits, but the highway and the permissible weight of the road train.
Why has containerization made transportation cheaper
Before the container, the cargo lived in a "piece—by-piece world": bags, boxes, barrels - everything is different, everything requires manual transshipment, recalculation, and protection. The container was removed from the chain of unnecessary touches: once loaded and sealed, then the unit is moved. This reduced processing time and the risks of loss/theft, and most importantly, it allowed ports, carriers, and warehouses to standardize equipment and processes.
The conclusion is simple: a container is not a container, but a global compatibility agreement that saves time, money and nerves for all participants in the chain.
