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Container load calculator

How many containers your cartons actually fill - and whether it is space or weight that runs out first.

Size 1

How much of the published capacity you actually expect to use. 85 is typical; cartons do not tessellate and stack height is limited by crush strength, not by the roof.

mm

mm

mm

In m³, from your carrier's spec sheet. Left blank it is worked out from the dimensions above, which gives geometric volume - slightly more than a carrier would publish for the same box.

In kg, from the spec sheet or the CSC plate on the door. Left blank the weight limit is simply not checked.

Enter your carton sizes, how many of each, and what one weighs. The number of containers appears here.

How this is calculated

Usable capacity = published capacity x load factor
By volume       = total cbm / usable capacity
By weight       = total kg / container payload
Containers      = the higher of the two, rounded up

Single carton size, exact fit:
cartons = floor(box L / carton L) x floor(box W / carton W) x floor(box H / carton H)
taking the best of the six ways a rectangular carton can be turned

Assumptions

  • Container capacities and payloads shown here are carrier-published figures for a standard dry box, and carriers do not agree exactly. Both sources cited below differ from each other. The figures for your booking are on your own carrier's spec sheet and on the CSC plate of the container itself.
  • Published capacity is a geometric ceiling nobody reaches. The load factor exists because cartons do not tessellate, pallets waste floor space, and stack height is limited by carton crush strength rather than by the roof.
  • With more than one carton size the answer is estimated from total volume and the load factor, not fitted box by box. Fitting mixed cargo exactly is a three-dimensional packing problem, and a precise wrong number is worse than an acknowledged estimate.
  • The exact fit shown for a single carton size assumes cartons can be turned freely and stacked to the roof. Cargo marked this way up, or too weak to take the stack, will fit fewer.
  • Weight is only counted when every size has a weight entered. Without it the answer is a volume answer, and dense cargo reaches the payload limit with the container half empty.
  • On a custom container with the capacity left blank, the figure used is the geometric volume of the dimensions you entered. A carrier's published capacity for the same box is always slightly lower because of the corner posts, so that path errs on the optimistic side and the working line says which of the two you are looking at.

How this container load calculator works

Two limits decide how many containers a shipment needs, and a shipment is only as small as the worse of them. Space runs out first on textiles, furniture and packaging. Weight runs out first on tiles, fasteners, liquids and machinery, and those containers look half empty when the doors close.

This tool works out both and tells you which one binds. Enter each carton size, how many of each, and what one weighs, then pick the container. The result is the number of containers, the limit that decides it, and every step of the arithmetic printed underneath so you can check it or paste it into an email.

Weight is not optional to the answer. Leave it out and the tool says so, because a container count based on space alone is the wrong number for anything dense.

The two calculations, and why there are two

With one carton size the fit is exact and worth doing properly. A rectangular carton can be turned six ways, and each way gives a different number along the floor, across the width and up the stack. The tool tries all six and keeps the best, then prints the three figures so you can picture the stow:

cartons = floor(box L / carton L) x floor(box W / carton W) x floor(box H / carton H)

With several carton sizes an exact fit is a three-dimensional packing problem, and solving it approximately while presenting the answer precisely is how calculators mislead people. So the tool switches to volume against usable capacity, says on the result that it is an estimate, and leaves the stow to your forwarder.

That is the honest boundary, and it is the one most container loading calculators do not draw.

Why the load factor matters more than the container

Carrier-published capacity is a geometric ceiling. Nobody reaches it. Cartons do not tessellate, pallets waste the floor space around their footprint, and stack height is limited by what the bottom carton can carry rather than by the roof.

Real loading lands ten to fifteen per cent below the published figure, so the tool applies an 85 per cent load factor by default and shows you the usable number rather than the theoretical one:

Usable capacity = published capacity x load factor
67.6 m3 x 85% = 57.5 m3

The field is editable because the right figure depends on your cargo. Uniform cartons floor-loaded to the roof might justify 90. Mixed sizes, awkward shapes or cargo that cannot be stacked belong nearer 75. A calculator that hides this behind a fixed number is the reason shipments fit on paper and not on the dock.

Worked example: 500 cartons in a 40ft

You have 500 cartons at 60 x 40 x 40 cm, each weighing 18 kg, and you want to know whether one 40ft standard takes them.

Volume. One carton is 0.6 x 0.4 x 0.4 = 0.096 m3, so 500 cartons are 48.0 m3. Usable capacity is 67.6 x 85% = 57.5 m3. By volume that is 48.0 / 57.5 = 0.84 containers.

Weight. 500 x 18 = 9,000 kg against a 26,840 kg payload, which is 9,000 / 26,840 = 0.34 containers.

The answer is one container, and volume is the limit. The box will be about 84 per cent full by space and only a third loaded by weight, which is exactly what you expect from light cargo.

Now make it tiles. Same cartons at 55 kg each: 500 x 55 = 27,500 kg, which is 27,500 / 26,840 = 1.02 containers. The volume has not changed at all, but the shipment now needs two containers and the second one carries almost nothing. That flip is the reason this tool asks for weight.

And the exact fit. A 60 x 40 x 40 cm carton in a 40ft standard, taking the best of the six orientations, fits 20 along, 5 across and 5 high - 500 cartons to the roof. It fits, with nothing to spare, which is a very different message from “84 per cent full”.

Container figures, and why carriers disagree

Every capacity and payload on this page is a carrier-published figure, and carriers do not agree with each other. On the 20ft, ONE publishes 33.1 cbm and Evergreen 33.2. On the 40ft payload, ONE publishes 26,840 kg and Evergreen 26,480 kg - a 360 kg gap that is real money on dense cargo and a real problem if you plan against the wrong one.

Both are cited at the foot of this page, and both carry their own note that individual containers vary from the published specification.

That is what the Custom container option is for. Each preset here is one carrier’s published specification, used whole - the tool will not quietly mix your capacity figure with somebody else’s dimensions, because a result assembled from two different boxes is worse than either. Choose Custom instead and the internal dimensions, capacity and payload fields appear, and every figure in the answer is yours. The authority for your shipment is your carrier’s spec sheet and the CSC plate on the door of the container you are given, not a default in a web page.

Nothing to install, no signup

The calculator runs entirely in your own browser as plain JavaScript, and your carton dimensions, quantities and weights are never transmitted anywhere. The site counts page visits with Google Analytics, but the page address it receives has the calculation stripped out of it first, so your shipment figures are not part of what it sees.

Your inputs are written into the page address as you type, so copying the link sends the exact calculation to a supplier or forwarder with every field already filled in. That link is the only thing that carries your numbers, and only if you choose to send it.

Frequently asked questions

How many CBM fit in a 20ft container?
Carrier-published internal volume for a 20ft standard dry container is about 33 cbm. ONE publishes 33.1 and Evergreen 33.2, which is the level of agreement to expect between carriers - close, but not one number. Plan against a usable figure rather than the ceiling, because at an 85 per cent load factor a 20ft holds roughly 28 cbm of real cartons. The gap is the space lost to imperfect stacking, pallet footprints and stack height limits.
How many CBM fit in a 40ft container?
About 67 cbm for a 40ft standard and about 76 cbm for a 40ft high cube. ONE publishes 67.6 and 76.2, Evergreen 67.5 and 76.4. At an 85 per cent load factor that is roughly 57 cbm and 65 cbm of cartons you can actually load. A 40ft holds a little over twice a 20ft by volume but carries slightly less payload, which surprises people shipping dense cargo.
How many cartons fit in a 40ft container?
It depends entirely on the carton, and the honest answer needs arithmetic rather than a number. A 60 x 40 x 40 cm carton in a 40ft standard fits 20 along, 5 across and 5 high once you take the best of the six ways it can be turned, which is 500 cartons before you consider weight. Change the height to 45 cm and the stack drops to 4 high, losing a fifth of the load. Enter your own carton above and the tool prints the along, across and high figures so you can check them.
What is the maximum weight for a 20ft container?
Payload for a 20ft standard is around 28,300 kg, and for a 40ft standard around 26,800 kg, both against a 30,480 kg maximum gross mass. The 40ft carries less because the box itself is heavier. Carriers differ here too - on the 40ft, ONE publishes 26,840 kg and Evergreen 26,480 kg, a 360 kg gap that matters on dense cargo. Take the figure from the CSC plate on the door of the container you are actually loading.
Why will my shipment not fit when the CBM says it should?
Because published capacity is a geometric ceiling, not a loading figure. Cartons do not tessellate perfectly, pallets waste floor space around their footprint, and stack height is limited by what the bottom carton can carry rather than by the roof. Real loading typically lands ten to fifteen per cent below the published number, which is why this tool applies a load factor by default. A 30 cbm shipment is not a 20ft container even though 33 cbm is published.
Should I use volume or weight to decide container size?
Both, every time, and take whichever needs more containers. Space runs out first on light bulky cargo such as textiles, furniture and packaging. Weight runs out first on tiles, fasteners, liquids and machinery, and those shipments reach the payload limit with the container visibly half empty. A calculator that only counts space tells a dense-cargo shipper the opposite of the truth, so enter a weight against every carton size and the result names which limit binds.
Do I need a 3D container loading calculator?
For a quote, no. A 3D stuffing diagram shows one theoretical arrangement, and no loader on a dock follows a generated plan - the cargo goes in the order it comes off the truck. What you need at quote time is how many containers to book and which limit binds, which is arithmetic you can check. A 3D plan earns its place later, for genuinely awkward mixed loads being stuffed under supervision, and it is a job for your forwarder's own system rather than a web page.
What is the difference between a 40ft and a 40ft high cube?
One foot of internal height. A 40ft standard is about 2,390 mm inside and a high cube about 2,695 mm, so the high cube adds roughly 9 cbm - about 76 against 67. Whether that is worth the freight difference depends on whether the extra height buys another layer of your carton. If your carton is 400 mm tall the standard takes 5 layers and the high cube takes 6, a 20 per cent gain. If it is 600 mm tall both take 4, and the high cube buys nothing.
Is it cheaper to ship one 40ft or two 20ft containers?
Usually one 40ft, because a 40ft rarely costs twice a 20ft and it holds a little over twice the volume. The exception is dense cargo, where two 20ft containers carry roughly 56,700 kg of payload between them against about 26,800 kg in a single 40ft, so anything heavy may need the pair regardless of price. Work out both limits first, then price the options - this tool gives you the container count and the LCL vs FCL calculator prices the alternatives.
What about 20ft high cube, 30ft or other container sizes?
They exist, and this tool deliberately ships no preset for them, because neither carrier cited at the foot of this page publishes a specification for them and a guessed default is worse than asking. Choose Custom container instead and enter the internal length, width and height in millimetres along with the capacity and payload. Those figures are on the CSC plate on the door of the container you have actually been given, which is the right source for any box including the four presets offered here.
What load factor should I use?
85 per cent is a reasonable default for palletised or hand-stacked cartons and is what this tool applies unless you change it. Go lower, nearer 75, for awkward shapes, mixed sizes or cargo that cannot be stacked high. Go higher, nearer 90, only for uniform cartons on a floor-loaded stow with a stacking height that genuinely reaches the roof. The field is editable because the right number depends on your cargo, not on the container.

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Sources & methodology

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Results are estimates for planning purposes. Verify with your carrier or customs broker before committing. This is not professional advice - see the disclaimer.

Every calculation runs in your browser. Nothing you type is sent to a server or stored anywhere.