Compliance Guide
How Do You Choose Between 20GP, 40GP and 40HQ? The Four Common Container Types Compared
How to choose between a 20-foot, 40-foot, 40 high cube and 45-foot container: a comparison of where each of the four types fits, how to judge light cargo against heavy cargo and how to read the loading rate, how to handle out-of-gauge and overweight cargo, and what a wrong container choice actually costs you.
- Four container types compared
- Includes light versus heavy cargo
- Working rules, reviewed 2026-09-22
Key figures (free to quote)
These are reference values for standard situations (complete documents, no inspection, not in a red-channel period); the carriers' and customs' current announcements prevail. Data reviewed 2026-09-27.
In short
- The core of container choice is not size, it is the weight limit.
- Whether the cargo physically fits is a volume question. Whether you can fill the container is a weight question. Plenty of people work out only the volume and never mention the weight, then discover on the loading day that the container is full but the weight is nowhere near the limit, or the other way round, that it is overweight and will not close.
- The order of judgement: first decide light or heavy, then compare whether the volume fits, and only at the end check the payload against the container's own weight limit.
- If any one of the three steps is skipped, you may end up changing the container type.
- One piece of experience: for heavy cargo look at the 20-foot first, for light cargo look at the 40-foot and the high cube first.
- The reason is that the difference in volume between container types is far larger than the difference in payload limits. More shipments get hurt by weight than by volume.
1. The four common container types compared
Treat the exact figures as measured, not assumed. The internal dimensions, volume and payload limit of each type vary with the condition of the box, the carrier and the specific unit. Before loading you must verify each shipment against the marking on the container actually used and against the carrier's weight limit. Do not carry the previous shipment's figures over.
| Container type | Shape and characteristics | Better suited cargo |
|---|---|---|
| 20GP (small box) | Shorter length and smaller volume, with a relatively generous payload limit | Dense heavy cargo where weight hits the limit first: steel, machinery, ceramic tiles |
| 40GP (standard dry box) | Longer, and clearly larger in volume than the 20-foot, but the payload limit does not rise in proportion to the extra length | Light cargo where volume hits the ceiling first: daily consumer goods, plastic products, packing material |
| 40HQ (high cube) | Greater internal height and more volume than the 40GP, with a payload limit close to the 40GP | Bulky cargo that is large in volume and light in weight: bags, foam, furniture, lighting |
| 45HQ and other high-cube types | Volume goes further still, but the routes it can be deployed on and its inland transit conditions are limited | Large-volume bulky cargo, and only after confirming the route and the road connection at both ends |
2. Judging light cargo, heavy cargo and the loading rate
Start by calculating the ratio of cargo volume to cargo weight. The larger the ratio, the lighter the cargo and the more space it occupies. The smaller the ratio, the heavier it is and the more it loads the scale. Which side of the line this ratio falls on is the first thing the container choice turns on.
- Light cargo, look at whether the volume will go in: once this cargo is full the weight is usually still far below the limit, so choose the largest volume available and use the space fully.
- Heavy cargo, look at whether the weight will hit the ceiling first: this cargo often leaves gaps inside the container while the weight is already close to the limit. Choosing a bigger box here just means paying for volume you cannot use.
- Calculate the loading rate on two separate bases, weight and volume. Looking at only one of them skews the judgement. Whichever reaches its ceiling first is the constraint that decides the container type.
- Stacking capability counts too: cargo that cannot be stacked reduces the usable height, so the theoretical volume is never fully used. This has to be handled separately in the stuffing plan.
3. Out-of-gauge and overweight cargo
Out-of-gauge cargo is not necessarily unable to enter the container, but it is not necessarily able to have the doors closed. First confirm whether the cargo can pass through the container opening, then whether it can be secured inside, and only then discuss how much of it will go in.
Overweight cargo has to clear two gates: the carrier's weight limit and the inland road weight limit. The carrier's limit decides whether it can be loaded on the vessel; the road limit decides whether it can be moved from the terminal to the factory or the consignee. If either one is not satisfied, the plan has to change.
Where the cargo falls outside what a standard box can take, the options are a breakbulk vessel or a special container such as a flat rack or an open top. The price structure of such a solution differs from a standard box, and it has to be applied for to the carrier in advance. It cannot be arranged at the last moment.
There is one more common answer to an overweight box: split it across two containers. The condition is that the destination port and the consignee accept split delivery, and that the documentation can close on its own for each part.
Whichever route you take, measure the actual weight, the external dimensions and the centre of gravity accurately. Building a special container plan on estimated figures carries a high risk.
4. What a wrong container choice actually costs
| The wrong choice | Where the extra money goes | Can it be recovered |
|---|---|---|
| A small box for light cargo | An extra container is booked, and the container freight plus the handling at both ends doubles | Changeable before loading; essentially irreversible afterwards |
| A big box for heavy cargo | You have paid for volume you cannot use, and the unit cost goes up | The container type can be changed before loading |
| Overweight discovered halfway through loading | The cargo has to be re-divided or moved to a special container, and the sailing has to be rearranged | The most expensive of the lot, and it usually brings a rolled shipment with it |
| The cargo will not go through the opening, or the doors will not close | Packing has to be stripped on the spot, or a special container has to be used | Handled on the spot, with no control over the timing |
| The road weight limit at the destination port does not match | The cargo has to be transhipped within the port, adding a leg of inland transport and storage | Manageable, but it adds cost and time |
5. Six common pitfalls
- Working out the volume and never the weight. This is the single biggest cause of a wrong container choice, and the most expensive one. Finding out on the loading day leaves almost no room to correct it.
- Treating the high cube as a general answer to fitting more. A high cube adds height, which does nothing for cargo that cannot be stacked high.
- Carrying the container type over from the previous shipment. Change the goods or change the packing and the constraints change with them. The container type has to be judged again for this shipment.
- Overlooking inland access and weight limits at the destination port. The fact that the container can be loaded on the vessel does not mean it can be delivered to the consignee.
- Not thinking about the securing method at the same time. Container choice and the securing plan are one thing. Done separately they easily produce a case where it fits but cannot be secured.
- Forgetting the condition of the container itself: fitness for cargo, water ingress, odour. Skip the exterior and fitness-for-cargo check at pickup and any problem you find afterwards is already too late.
Frequently asked questions
How do I tell 20GP and 40GP apart?
A 20-foot container is shorter and smaller in volume, but its payload limit is relatively generous. A 40-foot container is longer and clearly larger in volume, yet its payload limit does not increase in proportion to the extra length. So dense heavy cargo suits the 20-foot, while light cargo that hits the volume ceiling first suits the 40-foot. Confirm the specific figures against the marking on the container actually used.
What is the difference between a high cube and a standard container?
A high cube has more internal height than a standard container, so its volume is larger, while its payload limit is close to that of a standard container of the same length. It suits bulky cargo that is large in volume and light in weight. It does not help cargo that cannot be stacked high, because the extra height simply goes unused.
How do I tell light cargo from heavy cargo?
In practice, start by calculating the ratio of cargo volume to cargo weight. The larger the ratio, the lighter the cargo and the more space it takes. The smaller the ratio, the heavier it is and the more it loads the scale. Light cargo points you to the largest volume available; heavy cargo points you to the container with the most generous payload limit. This is more useful than memorising a fixed number.
Is the payload limit the same across container types?
No, and it varies with the condition of the container, the carrier and the voyage requirements. The payload limit is constrained at the same time by three things: the marking on the container itself, the carrier's weight limit, and the inland road weight limit. Before loading you must verify each shipment against the marking on the actual container and the carrier's requirement, and must not carry the previous shipment's figures over.
What do I do if I discover the container is overweight halfway through loading?
This is one of the more expensive situations. The usual options are to split the cargo across two containers, or to switch to a container with a more suitable payload limit. Either one can affect the sailing schedule and the documentation. Weight therefore has to be measured during the preparation stage and checked against the limits in advance, rather than worked out on the loading day.
Can out-of-gauge cargo go into a standard container?
It depends on two gates: whether the cargo can pass through the container opening, and whether it can be secured effectively inside. Only if both are satisfied is it workable. Otherwise you need to consider a special container such as a flat rack or an open top, or move the cargo on a breakbulk vessel. Special containers must be applied for to the carrier in advance and cannot be arranged at the last moment.
Can a wrong container choice be changed?
Before loading it can usually be changed, and while the goods are neither boxed up nor inside the terminal the cost of switching stays manageable. Once the container is loaded or has entered the port, a change means restuffing, rearranging the sailing and sometimes a rolled shipment, and the cost rises sharply. The container decision therefore belongs in the preparation stage.
What should I check when picking up the container?
At minimum do an exterior and fitness-for-cargo check: damage to the container body, water ingress, any odour or residue inside, whether the doors open and close properly, and whether the floor is sound. These directly affect cargo safety and how the container is judged during inspection at the destination port. If you find a problem, change the container before loading rather than after.
Data source
This page is a compilation of general working rules for reference only. It is not a customs, legal or price commitment.
Field requirements and declaration practices change with the regulations and with practice. Before actual declaration, the customs broker or PPJK must re-verify each shipment against the current rules in INSW and CEISA 4.0, and the official acceptance result prevails.
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