Loading Cable into Containers: The Weight Limit Arrives Before the Volume Limit

October 6, 2026

Ask a forwarder how much cargo fits in a 40-foot container and the answer comes back in cubic meters. That number is accurate, and for cable it is usually the wrong place to start. A drum of power cable is a compact mass resting on a small footprint, and a shipment built from drums will reach the container’s allowed weight long before it fills the walls.

The useful question is therefore not how much space the order occupies. It is which of the two limits, volume or weight, will arrive first, and how much of the other one you are going to pay for and not use.

Two limits, published side by side

A carrier’s container specification booklet gives both, and reading them together is what changes the planning. The figures below are the nominal data Hapag-Lloyd publishes for the general purpose and high cube general purpose containers a cable exporter would actually book.

Container	Inside length	Inside width	Inside height	Capacity	Tare	Max. payload	Max. gross
20′ GP, wooden floor	5,900 mm	2,352 mm	2,393 mm	33.2 m³ (1,172 ft³)	2,300 kg	30,200 kg	32,500 kg
20′ GP, steel floor	5,900 mm	2,352 mm	2,393 mm	33.2 m³	2,250 kg	30,250 kg	32,500 kg
40′ GP, wooden floor	12,032 mm	2,352 mm	2,395 mm	67.7 m³ (2,391 ft³)	3,700 kg	28,800 kg	32,500 kg
40′ GP, steel floor	12,032 mm	2,350 mm	2,392 mm	67.7 m³	3,750 kg	28,750 kg	32,500 kg
40′ HC, wooden floor	12,032 mm	2,432 mm	2,700 mm	76.3 m³ (2,695 ft³)	3,850 kg	28,650 kg	32,500 kg
45′ HC, wooden floor	13,556 mm	2,352 mm	2,700 mm	86.0 m³ (3,037 ft³)	4,700 kg	27,800 kg	32,500 kg

Three of those columns are weights and one is a volume. Maximum gross weight is a property of the box’s structure. Maximum payload is what is left after the tare weight is subtracted, and it is the only figure that describes what may go inside. Capacity in cubic meters says nothing about any of it.

The payload is the only figure that describes what may go inside

The density where the two limits cross

Divide payload by capacity and you get the cargo density at which the two limits meet.

Container	Max. payload	Capacity	Payload per cubic meter
20′ GP	30,200 kg	33.2 m³	910 kg/m³
40′ GP	28,800 kg	67.7 m³	425 kg/m³
40′ HC	28,650 kg	76.3 m³	376 kg/m³
45′ HC	27,800 kg	86.0 m³	323 kg/m³

The quotient is a threshold rather than a measurement. Cargo stowed denser than the figure will be stopped by weight before it is stopped by volume, and the remaining cubic meters in the container will never be filled. Cargo below it will cube out instead.

For a 40-foot general purpose container the threshold works out near 425 kg per cubic meter. A cable drum is copper, jacketing compound and a former, with very little of its volume given to air. Take any drum’s gross weight and divide it by the volume of its own envelope, and the answer lands on the weight side of that threshold by a wide margin. That single comparison is worth doing before a booking, because it decides which of the two columns in the container table the rest of the planning has to be built on.

Cargo above the crossover density is stopped by weight first

Why the high cube is usually the wrong box for cable

Set the three forty-foot options against each other, since that is where the choice actually sits.

Container	Capacity	Tare	Max. payload
40′ GP	67.7 m³	3,700 kg	28,800 kg
40′ HC	76.3 m³	3,850 kg	28,650 kg
45′ HC	86.0 m³	4,700 kg	27,800 kg

The 40-foot high cube adds 8.6 m³ of capacity over the standard 40-foot and removes 150 kg of payload, because the additional height is structure that has to be carried. On weight-limited cargo that is the worst of both directions at once: more volume that cannot be filled, less weight that can.

The 45-foot high cube repeats the trade at a larger scale. It offers 9.7 m³ more than the 40-foot high cube while giving up a further 850 kg of payload. Set against the standard 40-foot, it buys 18.3 m³ of extra volume and costs a full metric ton of payload.

The high cube earns its place when the cargo is bulky and light, because then the ceiling is the binding constraint and the extra height buys a real gain. For cable the extra height only pays if drums can be stacked into it, and that is a question about the drums rather than about the container. If the drums are not stackable, the high cube bills you for air.

The floor has its own numbers

A container’s payload is a total. The floor beneath it carries a separate set of limits, and they matter more for cable than for most cargo, because a loaded drum is precisely what the specification calls a concentrated load.

The booklet splits the two cases. A wooden floor accepts a forklift with a maximum axle load of 5,460 kg (12,037 lb), provided the contact area under each wheel is at least 142 cm² (22 in²), a condition the specification attributes to ISO 1496/I. A steel-floor container takes 9,200 kg (20,282 lb) on the same basis, which the booklet notes is valid for all commonly available forklifts.

Then comes the spread. For a 20-foot container the maximum spread load should not exceed 4.8 metric tons per running meter of length, or 7.6 metric tons on a steel floor. For a 40-foot container the figure is 3 metric tons per running meter, or 6.0 metric tons on a steel floor. The booklet adds a constraint that is easy to skip past: the load must not exceed maximum payload either.

Container	Wooden floor	Steel floor
20′	4.8 metric tons per running meter	7.6 metric tons per running meter
40′	3 metric tons per running meter	6.0 metric tons per running meter

Two containers of nominally similar strength therefore do not offer the same concentrated load per unit of length, and the longer box publishes the smaller figure. For cable this is the number to check before deciding how drums are laid out. Drums set down at intervals along the floor, each resting on a small area, are the exact case the concentrated load rule exists to catch.

Per-meter load limits are lower on the longer container

The door opening decides which reels load

A reel enters through the door, and the door is smaller than the interior in both directions.

The standardized minimum door opening is 2,337 mm (7’8") wide and 2,261 mm (7’5") high on a standard-height container, rising to 2,565 mm (8’5") high on a high cube. The matching minimum internal heights are 2,350 mm and 2,667 mm. On Hapag-Lloyd’s own 40-foot general purpose container the door opening is 2,292 mm high against an interior height of 2,395 mm, a difference of roughly 100 mm.

A reel standing on its flange, which is the orientation most cable ships in, has to clear the door header rather than the ceiling. A reel that would sit comfortably inside a high cube can still refuse to go in if the handling equipment cannot present it through the opening at a workable angle. Width is much less of a constraint: 2,340 mm of door against 2,352 mm of interior on the same box.

There is a tolerance clause to go with the dimensions. These are nominal figures, and the booklet allows a maximum difference of 10 mm (3/8") on length, width and height. Design the loading plan against the minimum internal figures the standard publishes, such as 12,029 mm for the length of a 40-foot container, rather than the nominal 12,032 mm.

Securing a dense load

Lashing devices on these containers are rated at a permissible load of 1,000 kg (2,205 lb) each, fitted to the top and bottom longitudinal rails and to the corner posts. A payload measured in tens of metric tons and a lashing point rated at one metric ton are two numbers that have to be reconciled by arithmetic rather than by judgment, and the count that falls out of it belongs on the loading plan before the box is stuffed. The interior floor surface sits 170 mm above ground level, and that is the surface everything is secured against.

What the packing list has to carry

A loading plan can only be as good as the packing data behind it. Before a booking, the list should be able to answer these.

Item	Why the loader needs it
Gross weight per drum	It is the input to every weight calculation in this article
Drum diameter and traverse width	Determines whether a standing reel clears the door opening
Whether drums travel upright or on their side	Changes the height a stack consumes
Stacking limit per drum	Decides whether high cube height is usable at all
Load per drum footprint	Checked against the concentrated load limit per running meter
Palletization and number of drums per skid	Sets the unit the forklift has to handle
Marks and numbers	Must match the shipping documents line by line

Timber in the container itself is already dealt with: the carrier states that exposed timber is treated according to Australian, European, Chinese and American requirements. Wooden packing and dunnage the exporter supplies sits outside that statement and is the exporter’s own responsibility.

FAQ

Does dense cargo fit better in a 20-foot container?

On a per-cubic-meter basis it does. The 20-foot general purpose container carries 30,200 kg into 33.2 m³, a ratio near 910 kg per cubic meter, against roughly 425 for the 40-foot. A heavy cargo therefore uses far more of a 20-foot container’s capacity and leaves less paid-for space empty. Whether two 20-foot boxes beat one 40-foot is a separate calculation that depends on freight rates and on how cleanly the order divides.

Is a high cube worth it for cable?

Only when the extra height can be used. The 40-foot high cube offers 8.6 m³ more than the standard 40-foot and 150 kg less payload. If the drums cannot be stacked into that height, the added volume is unusable and the payload loss is pure cost.

What limits the forklift that unloads the container?

The floor, not the cargo. A wooden floor accepts a maximum axle load of 5,460 kg (12,037 lb) when each wheel’s contact area is at least 142 cm² (22 in²). A steel floor accepts 9,200 kg (20,282 lb). The restriction applies to the machine being driven in.

Where do I find the payload of a specific box?

Maximum gross weight and tare are marked on the container, and the difference between them is the payload, which the carrier also publishes for each series. Treat the published payload as the ceiling: the per-meter concentrated load limits sit underneath it and can bind first.

Conclusion

Container capacity is quoted in cubic meters because volume is what limits most cargo. Cable is limited by weight, and the arithmetic that shows this takes two published figures and one division. Once a shipment is understood as weight-limited, the container choice stops being a question about space. The high cube hands back cubic meters that cannot be filled and takes away payload that could have been used, the floor imposes per-meter limits that a drum layout has to respect, and the door opening decides which reels load at all.

None of these constraints are hidden. They are published in the carrier’s specification booklet and marked on the box itself. The work is in reading them before the drums are built, rather than after they reach the port.

Container loading and export packing for cable

ZONG Cable supplies HDMI, USB, network, patch cord, fiber, power cord and communication cable, and states gross weight per drum, drum dimensions, stacking limits and palletization on the packing list before a booking is placed. When a shipment is weight-limited, send us the destination, the container type you are considering and the drum data, and we will set out how the load divides against the payload and the per-meter floor limits. The range sits under cable, the packing options are described on our packaging solution page, handling limits on site are covered in the guide to pulling tension and bend radius, the batch evidence that travels with a shipment is explained under test and inspection, and OEM support covers how packing is fixed for private-label programs.

Sources

Hapag-Lloyd, Container Specification booklet, General Information. Read directly for this article: maximum gross weights for 20-foot, 40-foot and 45-foot general purpose, flatrack and reefer containers; floor loads, giving a maximum forklift axle load of 5,460 kg (12,037 lbs) where the contact area per wheel is at least 142 cm² (22 in²) and citing ISO 1496/I, and 9,200 kg (20,282 lbs) for steel-floor containers; concentrated loads, giving 4.8 tons (10,582 lbs) per running meter for 20-foot containers and 7.6 tons (16,755 lbs) for steel floor, and 3 tons per running meter for 40-foot containers and 6.0 tons for steel floor, with the note that the load must not exceed maximum payload; the maximum-difference tolerance of 10 mm (3/8") on length, width and height; the permissible load of 1,000 kg (2,205 lbs) per lashing device on top and bottom longitudinal rails and corner posts; the 170 mm floor height; the gooseneck tunnel on all 40-foot containers; and the statement that exposed timber is treated according to Australian, European, Chinese and American requirements. https://www.hapag-lloyd.com/content/dam/website/downloads/press_and_media/publications/15211_Container_Specification_engl_Gesamt_web.pdf
Hapag-Lloyd, Container Specification booklet, General Purpose and High Cube General Purpose container pages. Read directly for this article: the ISO 668 table of external and minimum internal dimensions and door openings, giving 6,058 mm, 12,192 mm and 13,716 mm external lengths, 2,438 mm external width, 2,591 mm and 2,896 mm external heights, minimum internal lengths of 5,898 mm, 12,029 mm and 13,556 mm, minimum internal width of 2,350 mm, minimum internal heights of 2,350 mm and 2,667 mm, and minimum door openings of 2,337 mm wide by 2,261 mm or 2,565 mm high; the 20-foot general purpose container row, with inside dimensions of 5,900 × 2,352 × 2,393 mm, door openings of 2,340 × 2,292 mm, maximum gross 32,500 kg, tare 2,300 kg and maximum payload 30,200 kg at 33.2 m³; the 40-foot general purpose container, with inside dimensions of 12,032 × 2,352 × 2,395 mm, door openings of 2,340 × 2,292 mm, maximum gross 32,500 kg, tare 3,700 kg and maximum payload 28,800 kg at 67.7 m³; the 40-foot high cube general purpose container, with inside dimensions of 12,032 × 2,432 × 2,700 mm, door openings of 2,340 × 2,597 mm, maximum gross 32,500 kg, tare 3,850 kg and maximum payload 28,650 kg at 76.3 m³; and the 45-foot high cube, with inside dimensions of 13,556 × 2,352 × 2,700 mm, maximum gross 32,500 kg, tare 4,700 kg and maximum payload 27,800 kg at 86.0 m³. https://www.hapag-lloyd.com/content/dam/website/downloads/press_and_media/publications/15211_Container_Specification_engl_Gesamt_web.pdf
ZONG Cable range. https://zh-zong.com/cable/
ZONG Cable packaging solution. https://zh-zong.com/packaging-solution/
ZONG Cable test and inspection. https://zh-zong.com/test-inspection/