Shipping Container Types and Sizes: A Complete Guide
Shipping container types explained: 20 ft, 40 ft, high cube, reefer, open top, flat rack and tank, with typical dimensions and uses.
Shipping container types differ by size, wall design and temperature control. For most cargo moving through Iran, a 20-foot or 40-foot dry container is enough. Chilled, oversize or liquid cargo needs a special type. This guide explains each type, its typical size and when to use it.
Dimensions of shipping container types follow ISO 668, and container identification follows ISO 6346. The figures below are approximate and vary slightly by manufacturer and shipping line. Always confirm exact dimensions with your carrier before you book.
The standards behind shipping container types
ISO 668 sets the outside length, width, height and rating of freight containers. Outside width is about 2.44 m (8 ft) for all common boxes. Outside length is about 6.06 m for a 20 ft box and 12.19 m for a 40 ft box. Standard height is 8 ft 6 in (about 2.59 m). High cube height is 9 ft 6 in (about 2.9 m).
A TEU is a twenty-foot equivalent unit. A 20 ft container counts as one TEU. A 40 ft container counts as two TEU, also called one FEU. Height does not change the count. Ship capacity and port statistics use the same unit.
Dry containers: 20 ft, 40 ft and 40 ft high cube
The dry container is the standard choice. It has closed walls and a door at one end. It suits boxed, palletised and bagged goods. The table shows typical inside dimensions.
| Type | Typical inside size (m) | Volume | Best for |
|---|---|---|---|
| 20 ft dry | 5.9 × 2.35 × 2.4 | about 33 m³ | Heavy, dense cargo |
| 40 ft dry | 12.0 × 2.35 × 2.4 | about 67 m³ | Bulky, palletised cargo |
| 40 ft high cube | 12.0 × 2.35 × 2.7 | about 76 m³ | Light, tall cargo |
To choose between 20 ft and 40 ft, compare weight and volume. Dense goods such as stone, tiles or packed chemicals usually reach the weight limit before the box is full. A 20 ft container then makes more sense. Light, bulky goods such as plastic ware or textiles fit better in a 40 ft or high cube.
An empty 20 ft box weighs about 2.2 tonnes. An empty 40 ft box weighs about 3.8 tonnes. Your usable payload depends on the box's maximum gross weight, the line's limits and road or rail limits. You cannot always load up to the ISO ceiling.
Special shipping container types: reefer, open top, flat rack and tank
When cargo does not suit a dry box, one of these types may fit.
- Reefer (refrigerated): Holds a set temperature for the whole voyage. Thicker walls reduce inside space; a 40 ft reefer holds about 58 m³. It carries fruit, dairy and medicines, and needs a power socket at the port and on the ship.
- Open top: Has a removable roof. Cargo is lifted in from above by crane. It suits goods taller than the door.
- Flat rack: Has only a floor and two end walls. It carries machinery, pipes and out-of-gauge or heavy cargo.
- Tank: A standard tank inside a container frame. It moves liquids or gases.
These shipping container types are scarcer than dry boxes and may carry extra charges. Out-of-gauge cargo must be declared to the line before booking. For oversize loads, see our guide to industrial machinery shipping on flat rack and open top.
How to read a container code (ISO 6346)
Every container carries an identifier such as CSQU3054383. It has four parts.
- The first three letters are the owner code, registered with the Bureau International des Containers (BIC).
- The fourth letter is the equipment category; U means a freight container.
- Six digits form the serial number.
- The last digit is a check digit that tests whether the code was recorded correctly.
A size and type code sits next to it. For example, 22G1 means a 20 ft box, 8 ft 6 in high, general purpose. Code 42G1 is a standard 40 ft box and 45G1 is a 40 ft high cube. The letters R, U, P and T mark reefer, open top, platform (flat rack) and tank types.
Choosing among shipping container types for cargo from or to Iran
Three questions guide the choice. How heavy is the cargo? How many cubic metres does it take? Does it need steady temperature or special dimensions? The answers usually point to one of the shipping container types above.
Most containerised cargo in Iran passes through Shahid Rajaee port. It lies on the northern shore of the Strait of Hormuz, just west of Bandar Abbas, and is one of the country's main container ports. Chabahar, on the Gulf of Oman, also has container berths. Supply of special boxes such as reefers or flat racks differs by port and by line. Ask before you sign a sales contract. Our article on container shipping from Iran covers port choice in more detail.
Royan Logistic is a Tehran-based international freight and logistics company that coordinates sea freight together with road and rail legs. See our sea freight page for the service. If your cargo will not fill a box, read FCL vs LCL shipping. Rules and tariffs change, so confirm current conditions with the shipping line and customs.
Frequently asked questions
How many shipping container types are there?
Trade relies on five main shipping container types: dry, reefer, open top, flat rack and tank. Most come in 20 ft and 40 ft versions, and dry boxes also come as high cube.
How many cubic metres does a 20 ft container hold?
A 20 ft container holds about 33 m³ inside. Usable space is smaller because pallets and lashing take room.
What is the difference between a 40 ft and a 40 ft high cube?
Length and width are the same. The high cube is about one foot (30 cm) taller and holds more. It suits light, tall cargo.
Can I load a container up to the ISO weight limit?
Not always. The maximum gross weight is printed on the container plate. Line, road and rail limits also apply. Give your carrier the real cargo weight before booking.
Plan your container with Royan Logistic
Send us your cargo type, weight, volume, origin and destination, and we will suggest a suitable container. Fill in the quote form to start.
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