Container types, dimensions and how to load them

ISO dimensions and cube

Container sizing is governed by ISO 668:2013 and its Amendment 1:2016, and the internal dimensions below are the ones that matter for planning because external dimensions tell you nothing about what fits inside. Cube is usually the binding constraint on FCL cargo; weight is the binding constraint on dense cargo.

Two notes on the table. A 40HC is not a 40ft box with more cube; it is 4.5 cm taller, and 4.5 cm of additional height is worth far more than it sounds for flat-packed goods and tall appliances. And the cube figures are the theoretical maximum — a real shipment loads to somewhat less once dunnage, gaps between pallets and the unusable space above a load that is not perfectly level are accounted for. For planning, use roughly 95% of the stated cube.

The 40HC / 40HQ question

If you have compared quotes, you will have seen both 40HC and 40HQ used for what appears to be the same box. They are the same box. They are both the 40ft general purpose container fitted with the 9.6 ft (2.9 m) high cube roof and door, giving the 265 cm internal height above. There is no separate 40HQ standard and no difference in capacity between the two names.

What does exist, and is a different thing, is the 45HC (45HQ): a 45ft high cube with 1354 x 249 x 269 cm internal and about 86 cbm. It is not an ISO size, is less widely available, and is not interchangeable with a 40HC when the vessel or the terminal only takes one of them. The 48ft and 53ft high cubes are also non-ISO: they are North American domestic boxes, built for the US domestic rail and truck market, and they do not belong in an ISO capacity calculation.

Practical consequence: when a quote says 40HQ, it means 40HC, and you can plan on 75.3 cbm and 265 cm of internal height. When it says 45HQ, confirm availability on the specific service before booking, because it is not something every sailing has.

Choosing a box for your cargo

The decision is mostly a three-way comparison between cube, weight and handling.

• Volume-bound cargo — furniture, packaging, finished goods in cartons, anything light and bulky — should default to a 40HC. The extra height costs little and frequently removes the need for a second container.
• Dense or heavy cargo — machinery, steel, ceramics, bottled goods, tiles — should default to a 20GP or a 40GP. A shorter box is easier to load evenly, easier to secure, and less prone to cargo shifting, and you are far less likely to hit a weight limit before you fill the volume.
• Oversized or irregular cargo — needs a specific equipment type, not a standard box.

To decide between FCL and LCL, use the crossover rule rather than guessing: below roughly 13–15 cbm an LCL rate is usually cheaper, because an FCL pays for the whole box whether you fill it or not. Above that, FCL generally wins, and the gap widens as volume rises. The full comparison is in our FCL vs LCL guide.

To estimate whether your goods will fit, work in cbm: measure the packed carton dimensions, multiply, sum, and add roughly 5% for gaps and dunnage. Then compare against the box cube. If you are palletising, remember that a standard 1200 x 1000 mm pallet occupies a footprint of 1.2 cbm before anything is stacked on it, which is why pallet count is a useful sanity check on a quote.

Weight limits and the US trap

Container weight limits are a chain, and the weakest link governs. A box that is perfectly legal on the ship can become illegal on the truck, and then illegal on the train.

• US rail limits are 24,000 kg for a 20ft box and 30,500 kg for a 40ft box. These are gross weights including the container itself.
• US road limits are typically 20,000 kg on a 40ft box (36,288 lb) on a standard combination, with 80,000 lb gross vehicle weight as the practical ceiling.
• Many other countries apply gross vehicle weight limits that are stricter, and some ports apply container-specific weight limits that differ again.

So a 40ft container loaded to 30,500 kg to satisfy rail very often cannot legally be moved by road in the United States. On inland moves from US ports this is a routine operational fact, and it is the reason a load plan that maximises cube can still fail on the last mile.

Check the weight limits for every country the container crosses, not just the destination, and check them before you load rather than after. The verified gross mass (VGM) declared at origin is a legal declaration: a container that is loaded heavier than its declared VGM can be refused at the origin terminal.

Loading technique that actually works

Most container damage is not caused by the voyage. It is caused by the cargo moving inside the box when the vessel works in a seaway, and by poor weight distribution. These are loading problems, and they are addressable.

• Heavy low and forward. Put the densest items on the bottom, against the front wall, and spread the load lengthwise. A container that is back-heavy will lift and slam when the ship pitches.
• Even distribution across the width. A load that leans to one side twists the box and damages the doors and the roof rails, and it is a safety problem on the ship.
• Fill the gaps. Use dunnage, blocking and bracing so that nothing can shift more than a few centimetres. Soft bags of dunnage, cardboard and foam work; the goal is to remove play, not to build a wall.
• Use the lashing points and twist locks properly. Know that the lashing rings inside a standard box are generally not rated for lifting, and that the corner castings and the twist locks are what actually secure the container to the ship.
• Strap and wrap. Film and strapping keep stacks together and keep the load from shedding dunnage.
• Protect the floor and the walls. Cardboard, plywood or heavy tarpaulin between the floor and the cargo, and against the walls, prevents the container from marking the goods and the goods from marking the container.

Loading supervision — a representative at the factory during stuffing — costs little relative to the cargo and catches the majority of these problems while they are still fixable. The photograph of a correctly stuffed and sealed container is also the document you will need if there is a claim, and it is far better evidence than anything you can reconstruct afterwards.

Packaging, pallets and ISPM-15

Any wood packaging travelling internationally must comply with ISPM-15: heat-treated to a specified core temperature and permanently marked with the IPPC mark. This applies to pallets, crates, dunnage and skids. Non-compliant wood is treated as a biosecurity risk and can be held, fumigated, re-exported or destroyed at the destination, and Australia, New Zealand, the EU and several other destinations enforce it strictly.

Practical rules: buy ISPM-15 pallets from a supplier who can show the stamp, mark them yourself if you build them, and do not assume a plain wooden pallet is fine because it is going to a developed market. For goods that must survive a wet voyage, a moisture barrier matters more than almost anything else in the pack — a dry container with a leaking roof will do more damage than rough handling.

For the broader picture of what else has to travel with the container, our documents guide covers the paperwork side, and the cost guide covers what these choices do to the invoice.