In international shipping, containers are the backbone of global trade. Understanding the different types of containers, their weight and volume limits, and the rules around overweight containers is essential for freight forwarders, shippers, and consignees.
1. Types of Containers
The most common container sizes and types include:
20GP (20ft General Purpose) – standard dry container
20HD (20ft Heavy Duty) – reinforced heavy-load container designed for dense cargo
20OT (20ft Open Top) – open top for oversized cargo
40GP (40ft General Purpose) – standard dry container
40HQ / 40HC (40ft High Cube) – high cube container, extra height for voluminous cargo
40RF (40ft Reefer) – refrigerated container
40RH (40ft Reefer High Cube) – high cube refrigerated container
45HQ (45ft High Cube) – extra-long high cube container
According to their function and use, ocean containers are generally classified as:
Dry containers (GP)
High cube dry containers (HQ / HC / GH)
Garment containers (HT)
Open top containers (OT)
Refrigerated containers (RF / RH)
Tank containers (TK)
Flat rack containers (FR)
In freight forwarding:
“Big container” usually refers to 40GP or 40HC
“Small container” refers to 20GP
2. Weight Limits and Maximum Loading Volume
Each container type has its own maximum payload and usable volume:
20GP → Max loadable volume: ~28 CBM | Weight limit: 28 tons
40GP → Max loadable volume: ~56 CBM | Weight limit: 26.48 tons
40HQ → Max loadable volume: ~68 CBM | Weight limit: 26.28 tons
45HQ → Max loadable volume: ~75–78 CBM | Weight limit: 25.61 tons
Usage principle:
20GP is designed for heavy cargo (dense goods).
40GP / 40HQ are designed for light cargo (bulky goods with lower density).
Thus, dense materials such as minerals or metals are typically loaded in 20GP, while light but voluminous goods such as furniture or garments are better suited for 40HQ.
3. Overweight Containers (Heavy Containers)
The ISO standard defines overweight containers as those with a Maximum Gross Weight (MGW) exceeding 30,480 kg (30.48 tons). Such containers must display a triangular overweight warning label on the door. Containers below this threshold are considered general containers and do not require the label.
Carrier-Specific Rules
Shipping lines often apply their own overweight rules, which may be stricter than ISO standards. For example:
Many carriers classify a 20GP as “overweight” once cargo exceeds 21 tons.
If a 20GP is loaded with 23 tons, the shipper may need to pay an overweight surcharge depending on the carrier’s policy.
Each carrier sets a maximum allowable overweight. For example, some carriers allow up to 26 tons in a 20GP, but not beyond.
Overweight Fees
Not all overweight containers automatically incur charges. Some carriers allow applications for free heavy-duty approval, depending on their policies. However, whether the request is approved depends on the shipping line’s discretion.
Conclusion
Choosing the right container type and respecting weight and volume limits is critical for safe, efficient, and cost-effective shipping.
Use 20GP for heavy cargo.
Use 40GP/40HQ/45HQ for lighter, bulky cargo.
Always check carrier-specific overweight policies to avoid unexpected surcharges.
By fully understanding container types, loading capacities, and overweight rules, shippers and forwarders can minimize risks, optimize freight costs, and ensure smooth cargo transportation.
