What is a Metal Shipping container?
A metal shipping container is a portable, transportable steel box engineered to store goods and stack securely during intermodal transport. Most have two doors at one end and a corrugated steel body that provides the structure with rigidity.
These units are also known as ISO containers, steel storage containers, CONNEX boxes, or sea containers. The “ISO” label refers to the International Organization for Standardization, which sets the dimensional and structural standards that let containers move between ships, rail cars, and chassis trailers anywhere in the world.
What metal are shipping containers made of?
The dominant material is Corten steel (sometimes written COR-TEN), a high-strength low-alloy steel. Aztec Container’s office and storage units are constructed from durable Corten steel because it delivers strength without excessive weight.
Steel is not the only material in the category. Historically, the most common shipping-container materials are metal, wood, and plastic, but metal — specifically steel — dominates because it offers the structural integrity needed for stacking and long-term reuse.
The body panels are corrugated, meaning the steel is pressed into ridges. Corrugation increases panel stiffness and load capacity without adding material, which is why a relatively thin steel wall can support significant force.
Many steel containers also use marine plywood flooring set on steel cross-members. This flooring provides a durable work surface and helps protect the floors in Office Containers and storage Containers.
What sizes do metal shipping container come in?
Steel containers follow strict dimensional standards, so they stack and ship predictably. The three standard lengths — 10, 20, and 40 feet- cover the majority of storage and transport needs, with a standard width of 8 feet.
| Container | Length | Width | Height | Notes |
| 10 Foot Conex Container | 10 ft | 8 ft | 8.6 ft | Compact option for tight sites and smaller loads |
| 20 Foot Shipping Container | 20 ft | 8 ft | 8.6 ft | Equals 1 TEU; the global standard size |
| 40 Foot Standard Container | 40 ft | 8 ft | 8.6 ft | ~8,000 lbs empty; maximum standard capacity |
| 40-foot high cube | 40 ft | 8 ft | 9.5 ft | Extra foot of interior height for tall loads |
What are the main types of metal shipping container?
Steel containers are produced in several configurations, and the right type depends on what you intend to store or build.
| Type | Best suited for |
| Standard ISO steel | General dry storage and transport |
| Insulated | Temperature-sensitive storage and offices |
| Refrigerated/Reefer Containers | Cold or chilled goods |
| Office Containers | On-site workspaces, guard shacks, break rooms |
| Open-top | Loading tall or bulky items from above |
| Open-side / full side open | Wide-access loading and unloading |
How are metal shipping container customized?
A major advantage of steel construction is how easily it can be modified. Because the panels are weldable steel, fabricators can cut openings and reinforce them without compromising the frame.
Common modifications include roll-up doors, cargo doors, full side-open panels, industrial man doors, and windows. Custom containers are available in 10 Foot Conex Containers, 20 Foot shipping Containers, and 40 Foot Shipping Containers.
For workspace builds, steel office containers can be outfitted with full insulation, electrical packages, air conditioning, plumbing, and ground-level access. Floor plans range from a 10-foot guard shack to a 40-foot half-office/half-storage layout.
Security features are typically welded in as well. A secured lockbox shields the padlock area, and units are built to be lockable by default.
New vs. used Metal Shipping containers
Both new and used steel containers are widely available, and the choice usually comes down to budget versus appearance.
- Used containers are durable, structurally sound, and significantly more affordable. They are a strong option for buyers who prioritize function over a like-new exterior, and they can be resold or rented long-term.
- New (or “one-trip”) containers offer a cleaner finish and minimal prior wear, which matters most for office conversions, retail builds, and customer-facing installations.
Aztec Container offers refurbished pre-owned units updated with the components needed for continued use, and regularly carries chassis for most container sizes.
How to choose the right metal container size?
Matching the container to the job prevents both wasted space and capacity shortfalls. Use this quick framework:
- Choose a 10-foot Conex Container for tight lots, small tool storage, or guard-shack conversions.
- Choose a 20-foot Shipping Container, the most common size, for general storage by contractors, auto shops, restaurants, schools, and homeowners.
- Choose a 40-foot standard Container for large-volume storage and equipment.
- Choose a 40-foot-high cube when vertical clearance matters, such as racking, machinery, or retail and workshop builds.
When in doubt, the 20-foot steel container is the safest default: it balances footprint, capacity, and cost, and it aligns with the global TEU standard. Aztec Container has been supplying steel ISO containers, storage units, custom office builds, and CONNEX boxes since 1969. To match a configuration to your project, contact Our Expert team or call 1-800-399-2126.
Frequently Asked Questions (FAQs)
What metal are shipping containers actually made of?
Nearly all of them are built from steel — most often Corten steel, a high-strength low-alloy steel prized for its structural toughness. While metal, wood, and plastic have all been used in the broader container category, steel dominates because it stacks, welds, and holds up to repeated reuse.
What is Corten steel, and why is it used for containers?
Corten (COR-TEN) is a high-strength low-alloy steel, sometimes called weathering steel. Container builders favor it because it provides a strong, rigid body with a good strength-to-weight ratio — exactly what’s needed for a box that has to stack and carry heavy loads.
Are “metal shipping containers” and “steel storage containers” the same thing?
For practical purposes, yes. The terms, along with ISO container, CONNEX box, and sea container — all describe the same steel box. “Shipping” emphasizes transport, while “storage” emphasizes on-site use, but the underlying unit is identical.
What sizes do metal shipping containers come in?
The three standard lengths are 10, 20, and 40 feet, all at a standard 8-foot width. Standard height is about 8.6 feet, and high-cube units reach 9.5 feet. Custom builds also extend to 45 feet.
What’s the difference between a standard and a high-cube metal container?
Height. A standard 40-foot container is roughly 8.6 feet tall, while a 40-foot high cube adds a full foot to reach about 9.5 feet. That extra clearance makes high cubes popular for tall equipment, racking, and retail or workshop conversions.
How much does a 40-foot metal shipping container weigh?
A standard 40-foot steel container weighs approximately 8,000 lbs empty. The exact figure varies by manufacturer and whether the unit is standard or high cube, but 8,000 lbs is a reliable planning number.
Can a metal shipping container be customized?
Yes, extensively. Because the body is weldable steel, fabricators can add roll-up doors, cargo doors, full side openings, man doors, and windows, plus insulation, electrical, air conditioning, and plumbing for office builds. Custom sizes run from 10 to 45 feet.
What’s the difference between new and used metal containers?
Used (or refurbished) containers are durable and budget-friendly, ideal when function matters more than finish. New or “one-trip” units have a cleaner exterior with minimal wear, which is better suited to office conversions and customer-facing installations.
What is a CONNEX box?
“CONNEX box” is another name for a steel ISO shipping container. The term originated in logistics and is used interchangeably with sea container, shipping container, and steel storage container.
Can I rent a metal shipping container instead of buying one?
Yes. Steel containers are available for both purchase and monthly rental. Renting suits temporary projects and short-term storage needs, while buying makes sense for permanent installations or long-term use. Aztec Container offers sales nationwide and rentals in California.