Ocean freight has become the most commonly used and cost-effective(Container Size) way in international shipping. If you are importing from overseas, there is chance to deal with shipping containers. However, there are plenty of container size and types to meet various shipping requirements. Take a 40 foot HQ shipping container for example, it is capacious enough to load up to 68 CBM or 22 ton of goods.

But exactly which kind of container is the best option for your goods, and what are their differences? For most importers, this question remains complicated to answer.

For your better understanding, in this article, we will explain everything concerning shipping container, such as container sizes, container types and container markings in detail.

Table of Content

Chapter 1 The Most Common Shipping Containers Sizes

Chapter 2 Tips you should know when choosing container

Chapter 3 10 of the Most Commonly Used Container Types

Chapter 4 Shipping Containers Markings

Chapter 1  The Most Common Shipping Container Size

Dry containers are the most widely used container type. As for the container size, 8ft, 10 ft, 20ft, 30ft, and 40ft container are the common sizes. Thus, in this part, we list the Container dimensions, weights and specifications of these container sizes. We try to be as accurate as possible however the figures may differ depending on manufacture and conversion.

1. Standard External Container Dimensions

2. Standard Internal Container Dimensions

Chapter 2 Tips You Should Know When Choosing Container Size

1. Make full use of container volume

The supplier’s calculation of goods CBM may not be accurate, that is to say, the CBM the suppliers tell you may be higher or lower than the actual one. In this case, it is suggested to order larger quantity of products than calculated to avoid empty space in container. If some goods are left behind when the container has been fully loaded, you can keep them in warehouse or load them in next container. If possible, return them to suppliers who might accept your request. In most cases, the freight forwarders, owning to their rich experience in cargo loading, can arrange goods very skillfully and spare no space in container. They can even stuff 30 CBM goods into a 28 CBM container.

2. Confirm the weight limitation to avoid overweight

We list the container sizes and the corresponding CBM and weight at the beginning of the article, but when it comes to loading container, you still need to confirm it with the freight forwarder beforehand.

On one hand, different shipping companies have different restrictions on the container weight. On the other, for different shipping routes and shipping Season, the weight limit on cargo differs a lot. Take the weight limit of 20GP container for example, in Southeast Asia line, 24 tons of goods is usually allowed. For Dubai, 20 tons is not a big deal. But for the United States, cargo shall not exceed 17 tons. During the off-season, freight forwarders might also pick up some overweight containers, but during the peak season, they seldom do.

3. Choose the container types that best fit your cargo

The dry containers are commonly used to transport cargoes in sea shipping. But when you are going to ship perishable products, the 30-45 days of shipping duration in the sea will be a great disaster for the goods. Nay, the air freight is too much costly though it saves us time. In this case, the refrigerated container will do you a favor. The constant low temperature inside the container will help keep your goods fresh however far distance it travels.

There are also many special containers for your choice. To name a few, the open top container is introduced majorly for over oversize goods, fluid tank is adopted to carry the liquid such as glucose, soy sauce, beer, and cooking oil. Animal containers are used to ship poultry such as sheep, cows, chicken and ducks at sea. Car carrier containers are for shipping vehicles overseas.

For some cargoes, it’s better to use bulk carrier instead of shipping container. The bulk carrier is specially designed to transport unpackaged and loose bulk cargo, such as grains,coal, ore, steel coils and cement.

4. Find a freight forwarder or sourcing agent to consolidate the good

Each container has its maximum cargo weight and volume. However, it is difficult to utilize both maximum weight and maximum size at the same time. Taking a 20-foot standard container as an example, the maximum CBM is 28 and the weight is 17 ton. If you load with overweight cargo such as metal, most container space will be empty when it reaches weight limit. But if you are loading over-size but light products such as plush toys, it may only contain 3 tons of plush products when the 28CBM container is full.

In this case, you can consider cargo consolidation. Freight forwarders or buying agents can collect different goods into their warehouses, estimate the size and weight of the goods, and make plans to integrate metal materials and plush toys into one container. In this way, we can effectively utilize the capacity of the container.

5. The bigger the container, the more cost-effective the container

We listed several common container types in the beginning of the article, but which container is more economical to choose? In general, the larger the container, the cheaper the unit cost.

We illustrate with a table of data. Below is the shipping cost of different size of containers from Shanghai Port in China to Kabul Port in Afghanistan.

From this table, we can could see that within the same shipping time, the unit cost decreases as the container size increases. The unit cost of the 40 foot HQ is nearly 50% less than that of the 20 foot GP container. It is a significant cut on cost.

6. Some special products are not allowed to be shipped in containers

In fact, most of the goods can be shipped by sea in containers, and only a few are not suitable. The goods that cannot be shipped by containers are:

a. fresh goods, for example, live fish, shrimp, etc., because shipping by sea takes longer than other modes of shipping. If fresh goods are shipped in container, the goods will deteriorate during transportation.

b. If the weight of the cargo exceeds the maximum weight limit of container, such cargo cannot be transported by container.

c. Over size cargo cannot be shipped by container. Some large accessories are super high and wide. These cargoes are better to be shipped by bulk carriers or shipped on the deck.

Chapter 3  10 of the Most Commonly Used Container Types

1. Dry Containers

Dry Containers are most commonly used containers. For most of the products, you can ship in dry containers. They are available in sizes of 10 feet, 20 feet, and 40 feet.

2. Flat Rack Shipping Containers

Flat Rack containers are used to load over-size items, such as construction equipment, building supplies, or heavy machinery. The containers have 2 sides that can be folded to fit different cargo.

3. Open Top Shipping Containers

Open top containers are containers without top but usually covered with a removable tarpaulin roof, and are commonly used to contain over-height cargos.

 4. Tunnel Shipping Container

Tunnel containers, also known as double ends containers, are similar to a dry container. The container, with openings on both ends, looks like tunnel and has thus won the name of tunnel container. With two ends open, tunnel containers make it easier to load and unload.

5. Side Open Shipping Container

In contrast to dry container or open top container, side open container, as its name infers, opens on the side to meet the specific loading and unloading requirements.

6. Refrigerated ISO Shipping Containers

Refrigerated ISO Containers (also called Reefer containers) are used to preserve fresh goods such as fruit or seafood in shipping.

7. Insulated Shipping Containers

Insulated containers come with a regulated temperature control device. They are most suitable for transportation of products in long distance.

8. Cargo Storage Roll Shipping Containers

Cargo storage roll shipping container is a foldable container. It is one of the specialized container units made for particular shipping purpose such as sets or stacks of materials. They are made of thick and strong wire mesh together with rollers that enables their easy movement.

9. Half Height Shipping Containers

Half height containers are half the height of a full sized dry container. They are used to transport goods that need easy loading and unloading.

10. Car Carrier Shipping Containers

Car carriers containers are specially made for car transportation in long distances. To prevent cars from damages, they come with collapsible sides.

Chapter 4  Shipping Containers Markings

1. The Name of Container Owner or Lessor

– This shows the owner or lessor of the container, for example, the shipping company ABC.

2. The Container Number

– The main identifier of the container. A container number has 7 characters which are in an alpha-numeric sequence. It consists of 4 letters and 7 numbers. The numbers are unique to a container and are never duplicated.

– First 3 letters: Owner code (e.g. ABC for ABC Line)*

– 4th letter: Category Identifier. U, J, or Z:

U for all freight containers
J for detachable freight container-related equipment
Z for trailers and chassis.

– First 6 digits: Serial number

– 7th digit: Check digit (see below in Point 3)

The owner code is registered from the BIC (Bureau International des Containers et du Transport Intermodal)

3. Check Digit

– It’s the last digit of the container number listed above. This number is used to identify whether the container number sequence is valid.

4. ISO Code

– International Standards Organisation under their code IS06346 assigns each container type a unique ISO Code so as to avoid any ambiguity in identifying the size and type of containers.

5. MAX. GW

– Max Gross Weight indicates the maximum weight that the container could load. The tare weight of the container is included in the Gross weight.


– Tare refers to the weight of an empty container. This is an important to be considered by all ship operators and planners as this weight needs to be included when preparing container stowage planning.

7. MAX. CW or Max. Payload

– This identifies the maximum weight of the cargo that can be packed in the container. This weight will be shown on the bill of lading and it does not include the container’s tare weight.

Shippers must ensure that this weight is not exceeded when calculating the weight of the cargo.

8. CU. CAP. or Cube

– This is the maximum volume in the cubic capacity of the container.

9. CSC, ACEP & Other Certifications

– A valid safety approval plate called CSC (Container Safety Convention) plate in accordance with the International Convention on Safe Containers of 1972 is a must for every legal and in-service container.

10. Classification society label for type testing

– This label identifies the classification society that has proven this container on its strength, cargo worthiness, and sea worthiness.

EJET sourcing is the leading sourcing agent in China, and has customers all over the world. We have long-term cooperation with a wide range of shipping companies in China. If you have any sourcing or shipping request, please feel free to contact, we will surely get you the right product at favorable price and get the best shipping rate for you.