Ocean container types: a complete overview of shipping containers

Ocean containers loaded on the ocean vessel

International ocean freight usually involves stacking coloured containers on a cargo ship – an image we have all seen. While shipping containers may just look like regular rectangular boxes to many of us, there’s actually a wide variety of different shipping containers with standardised measurements and sizes.

Thanks to an internationally agreed system of shipping or freight containers, the same ‘boxes’ can be used across different modes of transportation. Thus shipping containers are often known as intermodal containers – from ocean freight to rail and land freight. And although these containers may seem similar at first glance, knowing the different types of shipping containers is important for anyone looking to ship goods internationally using ocean freight.

The most obvious question about ocean containers is usually – how much cargo can you ship with it? Containers can also be categorised by type as well as size, however, and it pays to know that the container you are choosing is actually suitable for international shipping. In this article we try to give answers to all these questions.

History of ocean containers

The use of international standardised steel shipping containers dates back to the 1940s and 50s when both commercial shipping operators and the US military began developing such units. Previously, standardised shipping containers had been in use across Europe in the 1930s, but it was until the mid-1950s that the containers that we are most familiar with went into widespread use.

The goal for shipping operators was always finding the most efficient way for shipping cargo across oceans and other modes of transport. With globalisation came the need for standardising the shipping process across different countries and operators, thus leading to the invention of modern intermodal containers and their regulations, known as ISO standards.

Published between 1968 and 1970, ISO standards establish consistent rules for loading, transporting and unloading goods across the globe. The development and widespread use of internationally standardised shipping containers greatly helped global trade and had a major role in the world becoming more globalised.

Shipping container quality types

When looking for different shipping containers, you might come across terms like ‘as-is container’ or ‘wwt container’. These terms refer to the quality of the container. What different quality grades are there and why are they important to know?

Different quality containers are usually charged differently. While some cargo such as raw materials can often be shipped in regular dry cargo containers or open top containers, many goods have specific shipping requirements. The following container quality specifications are used to provide customers information about the quality, age and type of container – e.g. whether the container is air- or waterproof or not.


  • Grade A container – these are the highest quality containers, usually brand new with no scratches or wear marks.
  • One-trip container – brand new containers that have only made the trip from the manufacturer to the destination country. Mostly free of any wear marks, save for minor scratches.
  • Wind and water tight (wwt) container – containers that very rarely leak or have any holes. Container is considered wwt if no air or water can get into it. Usually more than 8 years old, divided into grades based on their quality.
  • Cargo worthy (cw) container – the most commonly used B-grade containers which have already made some trips but are still in working condition. Their price can depend on the quality and age of the container.
  • As-is container – no longer cargo worthy containers. These containers have either too much rust or too many structural issues which mean cargo might be damaged during the shipping process.

Which are the different types of shipping containers?

Most people associate shipping containers with colourful rectangular boxes onboard ships or at ports, waiting to be loaded. While the vast majority of shipping containers are known as ‘general purpose’ or ‘dry freight’ containers – the very same closed boxes in the image, used mainly for shipping dry goods – there are in fact many different types of shipping containers, differing by both their use, measurements and even shape.

Ocean containers come in different sizes and measurements, although 20’ and 40’ dry cargo containers are the most common
Ocean containers come in different sizes and measurements, although 20’ and 40’ dry cargo containers are the most common. © Pexels.

Although over 90 per cent of the world’s shipping containers are made up of dry cargo containers, even those differ in size. As one might guess, the measurements of your shipping container are extremely important as they determine how much cargo you can load into (or onto) your container and how much that will cost – different-sized containers are usually charged differently.

Some goods may also not be suitable for ocean freight with regular closed containers. Depending on your cargo type, different container types might be necessary – coal and fish have different shipping requirements, after all. Fortunately, the standardisation of ocean shipping containers has made choosing and understanding different container types very simple across the board.


Dry Cargo container (DC)

20ft Dry Container.

The most common container type is undoubtedly the dry cargo or dry storage containers, which make up approximately 90 percent of all shipping containers. These containers can be divided mainly into 20 or 40 feet sizes and are manufactured from either aluminium or steel. They are suitable for most types of cargo. Aluminium dry containers have a slightly larger payload than steel, and steel dry containers have a slightly larger internal cube.


Most common dry cargo container sizes are:

  • 20’ dry cargo container = 20’ DC
  • 40’ dry cargo container = 40’ DC


High Cube Dry Cargo container (HC)

40ft High Cube container.

High cube dry cargo containers are identical to the regular containers in all aspects except height. Being a foot higher, they allow for more cargo space. High cube dry cargo containers come mainly in the following dimensions:


  • 40’ high cube dry cargo container = 40’ HC
  • 45’ high cube dry cargo container = 45’ HC


Open Top container (OT)

20ft Open Top container.

Open top containers are another standard type of ocean container, which are mostly used to transport overweight cargo. The open top enables for easier loading and unloading of heavy or cumbersome cargo and instead of a steel or aluminium roof, they can be covered with a tarp.


  • 20’ open top container = 20’ OT
  • 40’ open top container = 40’ OT
  • 40’ open top high cube container = 40’ OT HC


Flat Rack container (FR)

20ft Flat Rack container.

With collapsible sides, flat rack containers are very flexible and suited for transporting a wide variety of goods, including extremely heavy cargo that needs loading from the top or sides. Collapsible and non-collapsible flat rack containers can come with or without walls.


  • 20’ flat rack container = 20’ FR
  • 40’ flat rack container = 40’ FR
  • 40’ flat rack high cube container = 40’ FR HC

Refrigerated container (RF)

20ft Reefer container.

Refrigerated containers or reefer containers are used to transport goods requiring temperature-controlled conditions in transit, such as fruit, vegetables, dairy products and meat. It is fitted with a refrigeration unit which is connected to the carrying ship’s electrical power supply.


  • 20’ refrigerated container
  • 40’ refrigerated container

Insulated or thermal container

These shipping containers have controls for regulating temperatures, usually for maintaining a higher temperature than regular containers. Suitable for long-distance transportation of temperature-sensitive products.


  • 20’ insulated container
  • 40’ insulated container

Special purpose shipping containers

The six main container types listed above are the most commonly used and seen in the industry but in reality, there are many different so-called special purpose shipping containers. These containers usually have a more narrow purpose which means they are suited for a specific type of cargo.

Such containers are:


  • Ventilated shipping container – the ventilation system allows for hot air to leave and fresh air to enter the container, which is good for certain types of goods. Most commonly used for shipping coffee, these containers are also sometimes called coffee containers.
  • ISO tank shipping container – used for transporting liquids and gases, the tank containers can hold a variety of cargo from oil to hazardous substances – you can read more about shipping dangerous goods here.
  • Tunnel shipping container – similar to standard dry cargo containers with doors on both ends, allowing for easier access.
  • Open side shipping container – standard-size dry cargo container with side doors for easier access.
  • Double doors shipping container – same as before, except doors can cover the entire side, allowing for best side access.


As you might guess by now, the shipping containers list doesn’t actually end even here. You can read about even more different types of shipping containers and their purposes here.

What are the measurements and loading capacity of ocean shipping containers?

The following table gives the measurements for the most common container sizes and types in the metric system. When choosing shipping containers, always confirm container sizes with your supplier to ensure you both are talking about the same types of containers.

 Internal length (m)Internal width (m)Internal height (m)Payload (kg)Cubic capacity (m3)
20 ft Dry Container5,902,352,3921 70033,2
40 ft Dry Container12,032,352,3926 80067,7
20 ft High Cube5,902,352,6926 50037,2
40 ft High Cube12,032,352,7026 50076,3
20 ft Open Top5,892,352,3528 22032,5
40 ft Open Top12,032,352,3426 50066,2
20 ft Reefer Container5,442,292,2727 70028,3
40 ft Reefer Container11,562,282,2529 52059,3
20 ft Flat Rack5,942,402,3530 14033,5
40 ft Flat Rack12,132,402,1440 00062,2


Ocean shipping containers come in many different shapes and sizes. For anyone looking to ship goods internationally in shipping containers, taking a moment to familiarise yourself with the different container types, purposes and measurements can save both time and money. It’s important to keep in mind that different containers have different costs.

While standard-size shipping containers such as 20’ and 40’ dry cargo containers will usually have fixed prices, special shipping containers usually require a direct quotation from the provider.