Planning an export container shipment

Sea freight is priced per container, not per cubic metre. So for an export order the whole quote turns on one integer: how many containers does this order fill, and of which type. Get it wrong upward and you have quoted freight you do not need. Get it wrong downward and you are absorbing a container that was never in the price.

That number is not something you read off a packing list. It is the output of a short sequence of decisions, each of which constrains the ones after it — what the cargo actually is, which limit it hits first, what it travels as, and which container mix you book. This page walks that sequence in the order you hit it.

Start with the packing list, not the container

The temptation is to open with the container, because the container is what you are trying to count. It is the wrong end. Until the cargo is described properly, every count downstream is a guess with a decimal point on it.

A purchase order tells you what was sold. A load plan needs something narrower: for each line, a length, a width, a height and a weight. Those four are mandatory — nothing can be planned without them, and an ERP export that gives you cartons and gross weight but no dimensions is not a cargo list yet.

Cargo-Planner takes the packing list as it comes out of the system: import the Excel file directly, then map the columns to the fields the planner expects. Units are set at import time, which matters more than it sounds — a file in millimetres read as centimetres produces a plan that is confidently wrong.

Then add the things a packing list never carries, because they are the properties that decide whether a count is real rather than theoretical:

• Weight per item, not just a shipment total. Payload is a per-container ceiling, so a total tells you nothing about where the load stops.
• Not stackable, for anything that cannot take another item on top. This is the single property most likely to change the answer, because a container’s usable volume is mostly vertical.
• Max load, where an item can be stacked on but only up to a point.
• Orientations, for anything that may not be turned or tipped.

If this customer orders the same articles every quarter, put them in the cargo library once. The next order arrives as SKUs to be pulled rather than dimensions to be re-keyed, and the stackability rules you worked out the hard way come with them.

Volume or weight: which ceiling binds

Every container has two limits — cubic capacity and payload — and only one of them ever binds. It is worth carrying that in mind on every container you plan, whatever you plan it with, because it decides what kind of problem you have.

If the cargo is light and bulky, the container runs out of cubic capacity with payload to spare, and the count is a packing problem: orientation, stacking, how the pieces nest. If the cargo is dense — castings, tiles, liquids, anything with metal in it — it reaches maximum payload with the roof still a long way off. Better packing then buys you nothing at all, because the constraint is not geometry; the only lever left is the equipment you book. Two orders of the same volume can therefore need a different number of containers, and the reason is not the packing.

What you should not have to do is work out which one it is by hand before you can plan anything. That part Cargo-Planner makes trivial: the workspace summary reports the volume and the weight for every container the plan used, alongside the space actually used in each direction, so the ceiling the load ran into is visible in the result. You read which limit bound rather than estimating it — which is the difference that matters on a mixed order, where dense and bulky lines sit on the same packing list and no single figure tells you which of them stopped the load.

If you want the underlying figures to hand — for a sanity check, or before there is a packing list to import at all — the dimensions and payload figures for each container type are the numbers to check an order against, and the container loading calculator will give you a rough count against a single container type in a browser without setting up a plan.

One correction to make while you are here. Packing lists carry approximate dimensions more often than anyone admits — a nominal carton size, a crate measured before it was banded. If yours are known to be soft, set an error margin, which interprets every cargo as a stated percentage larger than the file says. A plan built on optimistic dimensions is the most common way a container count comes out one short.

What the cargo travels as

The unit the cargo ships as is usually already decided by the time the order is confirmed — by the customer’s handling equipment, by the destination warehouse, or by whatever you did last time. Take it as a given here.

It does change what you are counting. A palletised order counts pallet footprints, and the pallet’s own height and deck become part of the arithmetic. A floor-loaded order counts cartons, and the plan is free to interlock them.

For a palletised shipment, build the pallets and the container in the same plan rather than in two passes: mark the items to be preloaded, add the pallet types as secondary equipment, and the nested calculation builds the pallets first and then loads those into the container. Where different articles belong on different pallet types, load in pins each one to the equipment it is allowed on.

The question of whether to palletise at all, and how to build a mixed pallet well, are both jobs of their own. They are not this one.

Choosing the container mix

Here is the decision the quote actually rests on: one 40ft high cube, two 20fts, or a 40ft standard. It is where planners want a rule, and it is where I would be most careful about giving one.

I would be very careful about offering a magic kg/m³ number here, because I do not think there is one that survives contact with an actual rate sheet. The cargo density tells you what is physically plausible. The commercial decision tells you what is cheaper. A 40ft HC gives you a lot of volume; two 20fts can be attractive when the cargo is heavy enough that weight becomes the limiting factor before volume does. But then you have freight rates, port costs, equipment availability, inland transport, handling, destination charges — and sometimes the simple question of whether the customer actually has somewhere to unload a 40-footer.

So the two halves of the decision belong to two different sources, and it is worth keeping them apart. The load plan answers: can this physically go in one 40ft HC, and if not, what is the best alternative? The rate sheet answers: of the physically viable options, which one makes commercial sense? Build a quoting process around a universal density threshold alone and it will hold until the price difference between a 40ft HC and two 20fts is unusual on a particular lane — at which point your beautiful kg/m³ rule is wrong overnight, and nobody notices.

In practice that means calculating the order against more than one equipment mix. Select the container types you are willing to book in the setup step and give each one a fixed container cost — the freight rate you would actually be quoted for it. The plan then minimises total cost rather than maximising how full each container is, which are two different answers whenever container types are priced differently. That is the whole mechanism most shippers need, and it is set where the equipment is chosen.

If you want to nudge the result beyond cost — a shorter used length, a lower stack, better stability — a secondary goal does that, and it is usually enough.

Nobody quoting an export order thinks in optimisation objectives. They think in trade-offs. A second container might cost more in freight but save a day of loading labour; slightly worse utilisation might buy a cleaner unloading sequence. The job of the software is to make those trade-offs explicit rather than hiding them behind “best utilisation”.

When the order does not fill a whole number of containers

The awkward case, and the common one: the order comes out at about 1.3 containers.

The first thing to say is that “1.3 containers” is a property of a spreadsheet, not of the cargo. An order that divides into 1.3 by cubic metres is not necessarily 1.3 containers once you plan it. Maybe the remaining 0.3 is all stackable and goes in. Maybe it is one awkward machine that destroys the loading pattern and costs you far more than its volume. That is the most useful thing a plan does at this stage: it can reveal that the commercial estimate was based on CBM when the real problem was geometry — while the quote is still a quote and not yet a commitment.

Once you know it genuinely does not fit, the options are to split the shipment, hold the balance for the next sailing, or upgrade the equipment and pay for space you are not filling. What decides it is not a planning question: it is the urgency of the cargo, the value of the stock, the production schedule at the destination, sailing frequency, and what splitting costs you in paperwork and handling downstream. Sometimes people split it. Sometimes they hold the balance. Sometimes they pay for an extra container and hate doing it. Airfreight is normally a much bigger escalation than that, not the default answer to a leftover 0.3 of a container.

What the plan can do is cost each option honestly instead of arguing about it:

• Cap the equipment. Max number of containers to be used sets an upper limit and reports whatever will not fit as unloaded items. That is your remainder, itemised — the list you take to the customer, rather than a percentage.
• Keep the order intact, or find out you cannot. With a consignment ID set, use at most a single container per shipment forces the order into one container and unloads the whole thing if it will not go, and entire shipments must be loaded or none refuses a partial. Both turn a soft question into a hard yes or no, which is what you want before you commit to a delivery term.

Turning the plan into the quote

The count is now settled, and three different people need three different things out of it.

Your own quote needs the container count and mix, which is the number the freight rate multiplies. The customer needs to see that the order is going in the equipment you have quoted, and a 3D arrangement is a better answer to “why is this two containers?” than a paragraph is — share the plan as a link set to read-only, and they open the interactive view in a browser without logging in. The people stuffing the container need a sequence they can follow, which is a PDF of the loading steps, and your own operations may want the same plan as Excel to reconcile against the packing list afterwards.

The point of exporting all three from one plan is that they cannot disagree. The count in the quote, the arrangement the customer approved and the sequence the warehouse works to are the same calculation, not three transcriptions of it.

When this order becomes every order

Everything above assumes one order, quoted once. If the same customer orders the same articles every quarter, the interesting question stops being “how many containers” and becomes “why are we deciding this again”. The cargo library is the first half of that answer; keeping the settings you arrived at, rather than rebuilding them, is the second. That is a different job, and worth doing deliberately once this shipment is out of the door.