Container Type Code According to ISO 6346
Container Type Code According to ISO 6346 is an internationally standardized alphanumeric code that enables precise and rapid identification of dimensions, type, and specific properties of freight containers. This four-digit code is an integral part of the complex identification system for freight containers, as defined by the ISO 6346 standard issued by the International Organization for Standardization (ISO). The standard ensures a uniform system for coding, identification, and marking of containers, thereby enabling smooth operation of global logistics and intermodal transport.
The code contains key information about length, height, type, and properties of the container, which allows customs authorities, carriers, ports, and logistics operators to efficiently handle millions of containers worldwide.
In-Depth Description and Purpose
In the modern world, where millions of containers are transported across continents every day, it is absolutely essential to have a unified, globally understandable identification system. Without it, efficient coordination between shipping companies, rail and road carriers, port terminals, and warehouses would not be possible.
The ISO 6346 standard was created to standardize coding, identification, and marking of transport containers. This system is mandatory for all containers used in international maritime transport, and its proper use is a key requirement of most ports and customs authorities worldwide.
The entire identification code (so-called container number) on the container has these parts:
| Part of Code | Description | Examples |
|---|---|---|
| Owner Code | 3 capital letters, registered with BIC, uniquely identifies the owner | HZKU |
| Category Identifier (ECI) | 1 letter: U (freight container), J (removable equipment), Z (chassis) | U, J, Z |
| Serial Number | 6 digits, unique within the fleet | 123456 |
| Check Digit | 1 digit, verifies the correctness of the previous code | 5 |
In addition to these mandatory parts, the four-digit size and type code is always indicated on the side of the container, which is the subject of this article.
Structure of Container Size and Type Code (ISO 6346)
The container size and type code is a four-digit alphanumeric data, usually located below the main identification number.
- First character: Container length
- Second character: Height and sometimes width
- Third and fourth characters: Type and properties of the container
Table: Length Codes (First Character)
| Code | Length | Meters | Note |
|---|---|---|---|
| 1 | 10′ | 2.99 m | rarely used |
| 2 | 20′ | 6.06 m | most common |
| 3 | 30′ | 9.12 m | – |
| 4 | 40′ | 12.19 m | most common |
| 5 | 45′ | 13.72 m | high-cube/long |
| M | 48′ | 14.63 m | North American market |
| P | 53′ | 16.15 m | North American market |
Table: Height and Width Codes (Second Character)
| Code | Height | Meters | Note |
|---|---|---|---|
| 0 | 8′ | 2.44 m | – |
| 2 | 8’6″ | 2.59 m | standard height |
| 5 | 9’6″ | 2.89 m | high cube |
| 6 | >9’6″ | >2.89 m | special |
| 8 | 4’3″ | 1.30 m | half-height |
Table: Type and Properties Codes (Third and Fourth Characters)
| Code | Container Type | Description |
|---|---|---|
| G1 | General Purpose | standard closed container |
| R1 | Refrigerated (Reefer) | cooling/freezing container |
| U1 | Open Top | open roof, covered with tarpaulin |
| P1 | Platform/Flat Rack | floor only + front walls |
| T1 | Tank | tank container for liquids/gases |
| H0 | Insulated | insulated container without active cooling |
| B0 | Bulk | for bulk materials, special discharge openings |
| V0 | Ventilated | ventilated container |
| S1 | Named Cargo | for specific goods |
Overview of Most Common Size and Type Code Combinations
| Code | Meaning |
|---|---|
| 22G1 | 20′ long, 8’6″ high, standard container for dry cargo |
| 45G1 | 40′ long, 9’6″ high (high cube), standard |
| 22R1 | 20′ long, 8’6″ high, refrigerated container (reefer) |
| 42U1 | 40′ long, 8’6″ high, open top |
| 22T1 | 20′ long, 8’6″ high, tank container for liquids |
| 25G1 | 20′ long, 9’6″ high (high cube), standard |
Practical Decoding Examples
Example 1:
- Code on container: HZKU 876543 2
- Size and type code: 45R1
- 4 = 40 feet length
- 5 = 9’6″ height (high cube)
- R1 = refrigerated container (reefer)
Result: 40-foot high cube refrigerated container belonging to HZ CONTAINERS s.r.o.
Example 2:
- Code: 22G1
- 2 = 20 feet
- 2 = 8’6″ height
- G1 = standard container for dry cargo
Result: 20-foot standard container for general cargo.
Container Types According to ISO 6346 and Their Use
1. Standard (General Purpose, G1)
- Closed steel box, suitable for most dry goods.
- Most common variant on the market.
- Can be stacked up to 7-9 containers high.
2. Refrigerated Container (Reefer, R1)
- Own cooling unit, insulated walls.
- For transport of food, medicines, chemicals – temperature maintenance from -25°C to +25°C.
- Must be connected to an electrical outlet on the ship/port.
3. Open Top (U1)
- Steel sides, removable tarpaulin on the roof.
- Suitable for heavy and bulky goods loaded from above (machinery parts, steel coils).
4. Tank Container (T1-T8)
- Internal stainless steel tank in a steel frame.
- For liquids (chemicals, food, gases).
- Designation T3/T4/T5, etc. distinguishes maximum working pressure and other parameters.
5. Insulated Container (H0)
- Thermally insulated walls, no active cooling.
- Protection against outside temperature fluctuations.
6. Platform / Flat Rack (P1)
- Floor and front walls only (fixed or collapsible).
- For transport of machinery, vehicles, construction equipment.
7. Bulk (B0)
- For bulk materials, special filling and discharge openings.
8. Ventilated Container (V0)
- Has built-in ventilation openings, suitable for coffee, cocoa, wood.
Technical Requirements for Marking
- All characters (letters, digits) must be at least 100 mm high.
- Marking must be done in a contrasting color to the container color.
- Codes must be clearly legible, resistant to weather and mechanical wear.
- All data (including size/type code) are mandatory.
Importance of ISO 6346 in Practice
Automation, Safety, and Efficiency
- Codes enable automated recognition (OCR systems in ports, camera cranes).
- Ensure proper stacking – for example, a tank container must not be placed next to dangerous goods.
- Allow planning of weight and load distribution on the ship.
- Ensure proper connection of refrigerated containers to electrical systems.
Customs and Regulatory Control
- Customs authorities use the code for quick identification of container type and contents.
- Required in electronic communication (e.g., customs declarations, electronic documents).
Intermodality and Global Compatibility
- Thanks to ISO 6346, any container can be used in international transport without further marking modifications.
- Inspection and compatibility in every port in the world.
Latest Changes and Digitalization in ISO 6346
- The ISO 6346 standard is regularly updated, with the latest update performed in 2022/2023.
- Expansion to include codes for new container types (e.g., for specialized transport – lithium batteries, LNG, etc.).
- Digitalization: BIC operates a global database where any container can be verified by number and type.
Frequently Asked Questions (FAQ)
1. What if the code on the container is illegible?
- The container must be identified manually, which can significantly delay the process at the port. In extreme cases, it may be held until identity is verified.
2. Are all containers marked according to ISO 6346?
- More than 99%25 of containers used in international transport are marked according to ISO 6346. Exceptions may be some inland or special container systems.
3. Where can I find a complete list of codes?
- On the BIC-code.org website or in the official ISO 6346 standard.
4. What is the difference between code 42G1 and 45G1?
- 42G1: 40-foot container, standard height (8’6″), common for dry cargo.
- 45G1: 40-foot container, increased height (9’6″, high cube), larger volume for light cargo.
5. Who manages the owner code registry?
- Bureau International des Containers (BIC), bic-code.org.
Conclusion
Container Type Code According to ISO 6346 is a fundamental element of global container logistics. It enables immediate, precise, and uniform identification of every container in the world. Proper marking is essential for safety, efficiency, and speed of the entire supply chain – from manufacturer through port to end customer.
With increasing digitalization, the importance of proper ISO marking is increasing further. Every participant in the logistics chain should know the importance of these codes and be able to read and use them correctly.
Czech Republic, Třebíč 
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