How shipping container codes reveal size, purpose, and global standards
Shipping containers display combinations of numbers and letters such as 22G1, 42G1, or 45G1 on their surfaces. These markings are not chosen randomly. They follow a strict international system that identifies the container’s dimensions, structural features, and intended use. This system is governed by ISO 6346, a global standard developed to maintain consistency and efficiency in container transportation across countries, shipping lines, and terminals.
This article explains how purpose codes are built, what specific information they convey, and why they are essential in global logistics operations. Beyond indicating size, these codes also reflect vital operational characteristics, including maximum payload capacity, floor load tolerances, and environmental compliance requirements—all critical for ensuring safe, legal, and efficient container handling in modern supply chains.
What is ISO 6346?
ISO 6346 defines the international standard for coding, identifying, and marking shipping containers. Introduced by the International Organization for Standardization (ISO) in 1995, this system establishes a universal language for container identification, ensuring that containers remain recognizable across carriers, terminals, and borders. By applying ISO 6346, shipping companies maintain consistent labeling practices that strengthen traceability, enhance safety measures, and streamline logistics operations worldwide.
The standard regulates all essential markings on a container, including the owner code, serial number, size, type, and any operational markings. Purpose codes such as 22G1, 42G1, and 45G1 specifically relate to the section defining the container’s size and type. Adhering to ISO 6346 is not just an industry best practice; it is crucial for meeting international safety and regulatory requirements. Authorities in regions such as Europe, Australia, China, and North America rely on these standards, especially for ensuring proper floor construction, timber treatment against pests, and maintaining safe load-bearing capacities.
Breaking down the container codes: 22G1, 42G1, and 45G1
Each container code, such as 22G1, 42G1, or 45G1, follows a specific structure that reveals critical information about the container’s dimensions and intended use. Understanding how these codes are built is essential for selecting the right container for cargo, planning logistics, and ensuring regulatory compliance.
The code structure breaks down as follows:
- First digit (2 or 4): Identifies the nominal length of the container.
- Second digit (2 or 5): Indicates the height and sometimes the width of the container.
- Letters (G1): Describe the container type and any key features.
A closer look at each example:
22G1:
- 2 = 20-foot container length
- 2 = Standard height of 8 feet 6 inches and standard width
- G1 = General purpose dry container
- Maximum gross weight: 32,500 kilograms
- Internal capacity: approximately 33.2 cubic meters
42G1:
- 4 = 40-foot container length
- 2 = Standard height of 8 feet 6 inches and standard width
- G1 = General purpose dry container
- Maximum gross weight: 32,500 kilograms
- Internal volume: approximately 67.7 cubic meters
45G1:
- 4 = 40-foot container length
- 5 = High cube height of 9 feet 6 inches
- G1 = General purpose dry container
- Maximum gross weight: 32,500 kilograms
- Internal volume: approximately 76.4 cubic meters
Breaking down these codes allows shippers, freight forwarders, and terminal operators to quickly assess the dimensions and capabilities of a container without needing a physical inspection. High cube containers like the 45G1 require special transport planning, particularly in areas such as Europe where bridge and tunnel clearances often limit allowable heights. Proper identification ensures safe routing and prevents costly logistical disruptions.
Important container specifications for 22G1, 42G1, and 45G1
Each container code provides more than just dimensions; it also reflects important structural specifications crucial for safe and efficient transport. Understanding these technical details is essential for operational planning and compliance with loading standards.
The 22G1 container, a 20-foot general purpose unit, has an internal length of approximately 5.9 meters and an internal height of about 2.39 meters. Its flooring, traditionally constructed from marine-grade plywood or bamboo, supports standard axle loads of up to 5,460 kilograms. This makes it suitable for general cargo without excessive point loading.
The 42G1 container, measuring 40 feet in length, offers an internal space of approximately 12 meters while maintaining the same standard height as the 22G1. Its internal volume nearly doubles that of the 20-foot unit, providing about 67.7 cubic meters. The floor structure is similar, although some newer models incorporate reinforced designs capable of tolerating slightly higher axle loads, particularly useful for concentrated cargo shipments.
The 45G1 High Cube container extends the standard internal height to roughly 2.69 meters. This increased vertical clearance accommodates voluminous cargo such as automotive components, industrial equipment, and oversized consumer goods. Some 45G1 models come equipped with steel flooring, allowing axle loads up to 9,200 kilograms. This specification makes them highly favored for heavy, dense loads frequently moved between major global ports such as Shanghai, Hamburg, and Los Angeles.
Additionally, 40-foot containers, including 42G1 and 45G1 models, often feature a gooseneck tunnel in the base. This recessed section allows the container to sit lower on specialized chassis trailers, improving road stability and ensuring compliance with height restrictions during overland transport.
Understanding the size and type codes
ISO 6346 assigns each shipping container a two-digit size code followed by a two-letter type code, creating a clear and internationally standardized specification that identifies the container’s primary characteristics.
The size codes (first two digits) define the nominal length and height or width combination:
- 2 = 20-foot container
- 4 = 40-foot container
- 5 = 40-foot High Cube container (increased height of 9 feet 6 inches)
The type codes (last two letters) describe the container’s function and structural features:
- G = General purpose container for dry cargo
- R = Refrigerated container (reefer) for temperature-sensitive goods
- T = Tank container for liquids or gases
In the case of the G1 designation, it refers to a basic dry cargo container intended for general freight. Some variants, such as G0, also exist, typically indicating minor design modifications like additional lashing points, enhanced ventilation, or slight structural adaptations tailored to specialized cargo requirements.
This coding system allows terminal operators, shipping lines, and customs authorities to quickly recognize the container’s dimensions and intended use without manual inspections. Major logistics hubs such as Singapore, Dubai, and Rotterdam rely on ISO 6346 coding for stacking, loading, customs clearance, and efficient yard planning.
For businesses needing official validation of container codes, the Bureau International des Containers (BIC) maintains the authoritative database for container size and type designations.
Purpose codes and their role in shipping
Purpose codes are a critical part of global shipping and logistics operations. They deliver essential information about a container’s dimensions, structural characteristics, and load capabilities, enabling fast and accurate decision-making throughout the supply chain.
Equipment handling
Terminal operators must know the exact specifications of each container to use the correct lifting equipment for loading, unloading, and stacking. In busy ports like Rotterdam and Hamburg, precise purpose coding ensures that containers are placed in the right positions—even in difficult conditions such as high winds and heavy rain. Accurate stacking reduces the risk of container shifts, structural stress, and operational delays.
Space planning
Ships, rail carriers, and trucks must allocate space according to container dimensions. High cube containers, such as the 45G1 with a height of 9 feet 6 inches, require specific stacking strategies to comply with maritime stability rules and maximum height restrictions. Failing to account for extra container height can jeopardize vessel balance or exceed road transport limits, leading to fines and safety risks.
Compliance and safety
Customs authorities and regulatory bodies depend on accurate container coding for inspections and documentation approvals. Details like maximum gross weight, axle loads, and floor strength directly impact whether a container meets transport laws. In Europe, for example, road axle loads are tightly regulated to protect infrastructure, while in North America, bridge clearance standards must be observed to avoid accidents during overland transport.
Incorrect or missing purpose codes not only disrupt operations but can also lead to fines, cargo damage, and legal liabilities. Assigning and verifying purpose codes such as 22G1, 42G1, and 45G1 is essential for maintaining efficiency, ensuring cargo safety, and protecting supply chain integrity.
How ISO 6346 improves container logistics
ISO 6346 has transformed container transportation by introducing a universal standard that strengthens logistics across the global supply chain. Its adoption delivers key advantages in several critical areas.
Traceability
A unified identification system allows containers to be tracked accurately across shipping lines, terminals, and national borders. Whether transferring cargo between ships at major ports like Singapore or moving containers by rail across the Eurasian Land Bridge from China to Europe, consistent coding reduces the risk of errors during handovers and improves visibility at every stage of the journey.
Safety
Accurate container identification ensures that handling procedures match each container’s design specifications. Proper lifting, stacking, and securing minimize the risk of damage, protect cargo integrity, and help prevent accidents during transit and loading operations.
Efficiency
Standardized coding simplifies stacking, yard management, and transport planning. Major logistics hubs such as Antwerp, Shanghai, and Los Angeles depend on ISO 6346 to maximize terminal throughput, avoid misplacement, and improve turnaround times. Standardization also reduces administrative overhead, allowing faster customs clearances and streamlined documentation processes.
Error reduction
By following consistent coding rules, shipping companies minimize the risk of container misidentification. This reduces costly operational mistakes, such as incorrect container placement or routing. Furthermore, innovations like enhanced steel flooring, often used in newer container models, can extend a container’s service life by up to 25%, supporting long-term cost savings and more sustainable shipping practices by reducing the need for early replacement.
At Pier2Pier, accurate container coding under ISO 6346 forms the foundation of seamless, dependable shipping solutions that help customers optimize their logistics and maintain regulatory compliance.
Where to find official type code information
For companies seeking verified container specifications, two authoritative resources provide reliable and up-to-date information.
BIC Code Database
The Bureau International des Containers (BIC) maintains an extensive database of container size and type codes, accessible at bic-code.org. The BIC database serves as the official industry reference, regularly updated to reflect changes in container designations and standards.
ISO 6346 Standard
The full ISO 6346 specification is published by the International Organization for Standardization and can be obtained through iso.org. This standard outlines the detailed requirements for container coding, including owner codes, serial numbers, and structural designations, ensuring uniformity across the global shipping industry.
At Pier2Pier, we combine technical knowledge with operational expertise to help businesses interpret container codes and maintain full compliance with ISO 6346. Our guidance ensures that logistics operations remain efficient, accurate, and fully aligned with international standards.
FAQ about ISO 6346 purpose codes and container specifications
Understanding how shipping containers are coded is crucial for optimizing logistics, ensuring safety, and maintaining international compliance. Below we answer the most common questions about ISO 6346, purpose codes like 22G1, 42G1, and 45G1, and how these standards impact global trade.
How is a shipping container code structured under ISO 6346?
A shipping container code under ISO 6346 combines two digits and two letters. The digits represent the length and height, while the letters describe the container’s type. For example, G1 designates a general purpose dry container used for most dry cargo worldwide.
What is the difference between 22G1 and 45G1 containers?
The 22G1 container is a standard 20-foot container with a height of 8 feet 6 inches, while the 45G1 is a 40-foot High Cube container with a height of 9 feet 6 inches. The 45G1 offers significantly more internal volume for bulky cargo.
Why is accurate container coding important in shipping?
Accurate container coding is essential for safe handling, stacking, customs clearance, and efficient logistics planning. Incorrect coding can lead to fines, operational delays, and accidents, especially when transporting goods across different infrastructure environments like bridges, tunnels, and port facilities.
What materials are used for container floors like in 22G1 and 45G1?
Standard container floors, such as in 22G1 units, are usually made from marine-grade plywood or bamboo. Some 45G1 High Cube containers feature reinforced steel floors capable of supporting higher axle loads, up to 9,200 kilograms, ideal for transporting dense, heavy cargo.
Where can I find official information about container size and type codes?
Official information on container size and type codes can be found at the Bureau International des Containers (BIC) database at bic-code.org. The full ISO 6346 standard is available through the International Organization for Standardization at iso.org for detailed specifications.
What are common challenges with High Cube containers like 45G1?
High Cube containers like 45G1 often face transport challenges due to their extra height of 9 feet 6 inches. They require special planning for clearance under bridges and tunnels, especially in regions with stricter infrastructure height restrictions such as parts of Europe.
Master container codes to streamline your logistics and stay globally compliant
Shipping container codes such as 22G1, 42G1, and 45G1 form the backbone of efficient international trade. Governed by ISO 6346, these codes define a container’s size, height, width, and intended use, enabling seamless coordination across shipping lines, terminals, and customs authorities worldwide.
Understanding purpose codes allows businesses to manage their equipment more effectively, optimize cargo planning, and maintain full compliance with international standards. Mastery of container specifications not only improves operational efficiency but also supports sustainable practices by maximizing cargo space and reducing unnecessary transport emissions.
If you want to ensure that your logistics operations meet global standards while operating as efficiently as possible, Pier2Pier is ready to assist you.
[Contact our experts today] to decode your container operations and elevate your supply chain performance.