What are ISO Containers? A Complete Guide

Shipping containers are becoming more and more popular for innovative uses far removed from their original purpose in the movement of goods. Whether it’s conversions into offices, homes and even home gyms – plus near-endless potential across a range of other conversions – shipping containers are becoming the go-to option for an affordable, reliable way of quickly creating space.

Containers can come in a range of shapes and sizes, but are mostly standardised to a few set configurations. This is to allow easy stacking on container ships, while also making them easier to place onto trains and lorries. These are known as ISO containers, and in this blog, we’re looking at what this means.

What is an ISO Shipping Container?

The short answer to this is that they are standardised containers built to strict international guidelines, allowing them to be used across ships, trains and lorries (which is why they can also be known as intermodal containers) without issue or delay. It allows containers to be moved seamlessly around the world without repacking at every stage.

The ‘ISO’ comes from the organisation that manages these standards, the International Organization for Standardization. They succinctly describe themselves as “bring[ing] global experts together to agree on the best way of doing things”. Their standards ensure containers are built to consistent sizes, strength requirements and safety levels. That’s why most containers you’ll see are the familiar 20ft and 40ft units, at a standard height of 8ft 6in, designed to stack neatly, travel safely and handle tough conditions without compromise.

ISO Container Standards

ISO container standards are thorough and apply to a series of different categories, each of which have their own number. There are many different standards that container manufacturers have to follow to ensure every unit meets the same expectations for size, strength and performance. Let’s have a quick look at just three of the key standards:

• ISO 668: This defines dimensions and ratings (such as total allowable weight), ensuring they can be stacked and transported worldwide.
• ISO 1496: This focuses on structural strength, ensuring containers can handle continued lifting, stacking and harsh seafaring weather.
• ISO 6346: This covers identification and marking, making every container traceable and easy to manage in the global supply chain.

Together, these standards keep global shipping efficient, safe and reliable, and ensure that all over the world, when you buy an ISO container, you know exactly which standards it meets.

ISO Container Identification Details

Let’s dive just a little deeper into ISO 6346, which deals with container identification. This standard requires every ISO container to come with unique markings that mean each unit can be tracked globally, wherever it may be in the supply chain.

The first is what’s known as the BIC (Bureau of International Containers) code, a four-letter code that identifies who the container belongs to. There’s also a six-digit serial number, unique to each unit, and then a check digit that’s used to confirm the rest of the number is valid.

There’s also a four-character size and type code, which tells you the container’s dimensions (first two characters) and purpose (last two characters). Without getting too deep, a code of 22G1 means a 20ft by 8ft 6 inch container for general-purpose use with passive venting. Finally, there are operational markings such as tare (empty) weight, maximum load and capacity information.

The History of ISO Containers

Modern ISO containers date back to the 1950s, when standardised steel containers were first introduced in an attempt to make transporting goods faster, safer and more efficient. By 1956, the first container ship carried goods without the need for unloading and repacking at each stage.

Following this, global standards were introduced to ensure every container could be stacked, lifted and transported seamlessly across ships, trains and lorries. This ultimately led to the ISO containers we recognise today. We’ve covered the full history in our guide to the history of shipping containers.

Benefits of ISO Containers

Cost Effective

Shipping containers are incredibly common, making them cheap to mass produce. This also means they are easy to get hold of. Estimates of how many there are in the world range from 20 million to 40 million, including a vast number that have been repurposed for a range of new uses after their life at sea has come to an end. This trend has been speeding up simply because containers are so affordable in the first place.

Versatile

Cost is always a factor, but versatility is essential in why more and more shipping containers are being used for things like housing, site offices, canteens, sales centres, home gyms and more. They not only provide a blank slate for whatever the owner wishes to create, but they are also built to be transportable, which is why they are often used for pop-up shops and other promotional activities where the entire unit can be driven to the next location quickly and easily.

Durable

Containers are also inherently strong and durable, having been initially designed to endure a decade or more of tough ocean-crossing conditions, as well as being lifted by cranes onto trains and lorries. Their steel construction makes them secure and long lasting. When you buy an ISO container, you know the unit has been built to these strict standards, so it will stand the test of time, remain waterproof and keep all contents secure.

ISO Container Types

Dry Storage

Dry storage containers are common, standard ISO shipping units. They are fully enclosed steel boxes designed for transporting and storing general goods. Available in a range of sizes, including 10ft containers, 20ft containers and 40ft containers, they’re secure, weatherproof and incredibly versatile.

Open Top Containers

Open top containers are designed for types of cargo that won’t easily fit through standard container doors. Instead of a fixed roof, they use a removable tarpaulin cover, allowing loading from above by crane. They can be useful for transporting sand, gravel and aggregate.

Side Opening Containers

Side opening units provide full-length access along one side, making loading and unloading much easier, especially for bulky items or when quick access is needed to items at the centre of the container. They’re ideal when access is just as important as storage.

Refrigerated Containers

Refrigerated containers, also often called reefers, are temperature-controlled ISO container units used to transport perishable goods like food or pharmaceuticals. They function like large mobile fridges, maintaining consistent internal temperatures regardless of the external conditions.

Ventilated Containers

Ventilated containers are designed to allow airflow inside the unit while still keeping bad weather out, helping to reduce moisture and condensation. This makes them ideal for transporting goods that need ventilation, such as agricultural products, where trapped moisture could cause damage.

Flat Rack Containers

Flat rack containers look more like reinforced platforms, with either fixed or collapsible end walls but no side walls or roof. They’re used for oversized or heavy cargo, such as machinery or vehicles, which won’t fit into a standard enclosed container. As ISO units, they maintain the same dimensions and stacking points.

Tank Container

Tank containers are specialised units designed to transport liquids, gases or chemicals. They consist of a cylindrical tank mounted within a steel frame that meets the standards of the ISO specification, allowing them to be handled like standard containers while safely carrying bulk liquids.

Applications for ISO Containers

As we touched on earlier, ISO containers are now used for purposes far outside their original intended use in international shipping. Just some of the many different modern applications include:

• Secure on-site storage for tools, equipment and materials
• Construction site offices and welfare units
• Container conversions such as gyms, cafes and retail units
• Temporary or modular office spaces
• Agricultural storage for feed, machinery or produce
• Pop-up shops and promotional units
• Workshops or mobile workspaces
• Emergency or disaster relief storage and accommodation

Containers offer an attractive blank canvas for near-limitless applications where secure, easily movable and affordable space is needed. If you can imagine it, a container can probably be converted into it.

Shipping Containers at KH Containers

We hope this article thoroughly answered what ISO containers are. Here at KH Containers, we have over a decade of experience finding the perfect containers for our clients’ needs. Whether you’re after an empty unit or a full conversion, our experts can provide ISO standard sizes such as 10ft, 20ft and 40ft units, in a range of container types.

Ease, trust and affordability are all part of our service, so whatever you’re looking for, contact us today and we’ll make sure you get the containers you need. Call us on 0333 577 3191, email henry@khcontainers.co.uk or use our online contact form to get in touch with our team. If you have any questions, we’re here to answer them, and you may also find the answers on our FAQ page.