What a load plan is, and how one gets made

A load plan is a document that says which cargo goes into which vehicle, where each item sits, and in what order it is loaded.

That is the whole definition. Everything else — the utilisation percentage, the 3D picture, the axle weights — is detail that hangs off those three answers. If a document does not answer all three, it is a packing list or a quote, not a load plan.

The word covers the same object in every mode. A sea container, a curtainsider, an aircraft ULD and a warehouse pallet are different shapes with different rules, and the question being answered is identical: given this cargo and this space, what goes where?

What a load plan contains

A usable plan has four parts, and most of the arguments about load planning are really arguments about one of them.

The cargo. Every item with its length, width, height and weight. Those four numbers are the minimum — no method, manual or automated, can place an item without them. Anything beyond that (stackability, orientation, destination, dangerous-goods class) narrows where the item may go rather than whether it can be described at all.

The equipment. Which containers, trailers or ULDs are available, and their real internal dimensions — not their nominal names. A 40ft container is not 40 feet on the inside, and the gap between the two is where most first-attempt plans go wrong. If you need those numbers, they are in the sea container, trailer and ULD references.

The rules. What may sit on what, what may not travel with what, what has to come off first. These are the part that never appears in a naive calculation and always appears in a real load.

The result. A position for every item, a count of vehicles, and something the loading floor can act on.

What a load plan is not

Three documents get called load plans and are not, and confusing them is a common way to arrive at the ramp with the wrong answer.

A packing list is an inventory. It says what is being shipped and how much it weighs. It says nothing about where anything sits, so it cannot tell you how many vehicles you need.

A stowage plan — in the vessel sense — allocates containers to slots on a ship. That is planning at one level up: the unit being placed is the whole container, not the cargo inside it.

A route plan answers where the vehicle goes, not what is inside it. The two interact, and that interaction is where multi-drop loads get expensive, but they are separate documents.

Why loads are planned at all

The reason is not tidiness. Three specific costs appear when a load is not planned properly, and they show up at different moments.

At quoting time, you commit to a number of vehicles before anyone has arranged the cargo. Guess high and the price loses the job. Guess low and you absorb an extra trailer at your own cost. This is the expensive one, because the mistake is priced in before anything physical has happened. Getting to a defensible number ahead of time is the whole point of working out how many pallets fit in a truck or what a consignment costs in loading metres.

At the ramp, the cargo does not fit the way someone assumed it would. The freight is already at the door, the vehicle is booked, and the options are to leave items behind or to reload from the start.

The version of this we hear about most often is not a geometry error at all. The cargo genuinely fits the container — the arrangement is sound, the numbers add up — and it still cannot be loaded, because it will not go through the door. A container’s door aperture is smaller than its internal cross-section, and a plan that only checked the internal dimensions has verified the wrong thing. The same failure has variants: the item at the top of a stack that nobody can physically reach to place, or the piece that would have to be lifted over cargo already loaded. This is the single most recurring frustration we hear about from planners, and in every case the layout was correct and the load was still impossible.

At the destination, the load is dense and unusable — the first delivery is at the headboard behind everything else, or the cargo has shifted because the weight sat wrong. A plan that maximises fill and ignores unloading order has moved the cost rather than removed it.

How a load plan gets made

Whatever the method, the same four steps happen in the same order. What changes is how much of each one a person does by hand.

1. Collect the cargo data — dimensions and weight per item, plus whatever properties constrain placement.
2. Decide the equipment — which vehicle types are available, and how many of each you are willing to use.
3. Arrange the cargo — the actual placement, subject to the rules.
4. Produce something usable — a document the yard, the customer and the driver can each act on.

By hand, step 3 is where it breaks down. A planner with experience can arrive at a good arrangement for a uniform load quickly — 26 pallets in a trailer is not a hard problem. The difficulty scales with mixed dimensions: every additional item size multiplies the arrangements worth considering, and the honest answer is that nobody evaluates them all. What actually happens is that the first workable arrangement is accepted, which is usually not the cheapest one.

In a spreadsheet, you get arithmetic — total volume, total weight, loading metres — but no geometry. Volume-based estimates are systematically optimistic, because they implicitly assume cargo is a liquid. Two consignments with identical cubic metres can need a different number of trailers, and the spreadsheet cannot see the difference.

In load planning software, steps 1 and 2 are data entry and step 3 is calculated. In Cargo-Planner the work is divided into four views matching the steps above: enter or import the cargo, select equipment from the library, calculate, then work with the resulting plan. Items that cannot be placed under the current rules are listed in an unloaded-items panel rather than silently dropped — which is the part that tells you your equipment selection was wrong, not your cargo data.

What “optimised” means, and what it does not

Software that arranges cargo is usually sold on utilisation, and utilisation on its own is a poor goal. A plan that fills a trailer to 96% and cannot be unloaded at the first stop is worse than one at 88% that can.

It is worth being direct about how little of the problem the packing algorithm actually is. Cargo-Planner’s first milestone, at the very beginning, was exactly what you would expect: arrange cargo at the highest possible utilisation, quickly. That milestone was reached and checked off. Everything since — years of it — has been about context: teaching the system the constraints that make a dense arrangement into a load that can actually be executed, and producing the information the people downstream need. A sea container has to be loaded from the bottom up, and its centre of gravity has to be kept inside a defined interval, because at some point that box is going onto a vessel and has to be safe there. The stack has to be reachable by the person building it. Note what the documentation for that setting says plainly: constraining the centre of gravity will most likely affect utilisation negatively. That is not a defect. It is the trade being made on purpose. Getting from a valid arrangement to a usable one is the hard part, and it is where the work is.

So the useful question is what the calculation is being asked to minimise. In Cargo-Planner that is expressed in a few explicit places rather than assumed:

• A secondary goal — minimise used length or height, or improve stability — applies once the vehicle count is settled.
• A cost function adds a cost per loaded container, so the plan can be pushed toward the cheapest freight bill rather than the fullest vehicle. These are two different answers whenever container types have different rates.
• Routing sequences loading by destination, so a multi-drop load comes off in the order it is delivered.
• Custom rules and the segregation table hold the constraints that are about what may be loaded rather than what it costs — including dangerous goods separation.

The general point survives the specific product: a load plan encodes a trade-off, and you should know which one you asked for.

A plan nobody can follow is not finished

The last step is the one most often skipped. A plan that exists only on the planner’s screen has not changed what happens in the yard.

A load plan also has more than one audience, and they want different things from it. The warehouse needs a sequence it can build — what goes in first, and whether the next item can still be reached. The forwarder or receiver moving the container afterwards is not interested in the layout at all; they want to know how far off centre the centre of gravity sits, because that is what determines how the box is handled and whether it is safe on a vessel. A tool that outputs a container layout and stops has served neither of them.

That means the arrangement has to leave the office in a form the floor can act on — a loading sequence rather than a final picture, since the person loading needs to know what goes in first. Cargo-Planner can show the loading order step by step, export the plan as PDF or Excel, or share it as a link that a customer or warehouse can open without an account.

Whether any of that survives contact with the loading bay is a separate discipline, and it is the difference between a plan and a loaded vehicle — see why loading instructions matter.

Where the standard advice is wrong

The trade advice everyone repeats, ours included, is to ship less air. It is the right instinct and it is the goal the whole exercise points at — but taken literally it is wrong, and it is worth saying so plainly.

Loading a container of any kind demands a certain amount of air. Cargo may need to be isolated from other cargo. The order of loading and unloading may make it cheaper to leave a gap than to reload at an intermediate stop. Sometimes the space exists for no better reason than that the item has to get through the door. In each case the empty volume is not waste, it is the price of a load that works.

The air in a container is not a demon to be driven out at any cost. It is an expensive asset, and it should be managed with care and thought — spent deliberately where it buys something, and not spent where it does not. That distinction is the entire difference between a packing result and a load plan: a plan accounts for how the cargo will actually be moved, and keeps it safe and economically viable across the whole journey, not just at the moment the doors close.

Where to go from here

Load planning gets specific fast, and the specifics are where the money is:

• Cargo that does not fit inside the legal envelope is a different job with its own sequence — see moving out-of-gauge cargo by road.
• One vehicle with several consignees is a sequencing job before it is a packing job — see planning a multi-drop trailer load.
• When the same load repeats — a tour, a run of dates, a standing pack — the problem is standardisation rather than arrangement: see planning the truck pack for a touring production.
• Quoting an export order comes down to a container count and a container mix — see planning an export container shipment.
• When the unit being shipped does not exist yet, the container decides its dimensions rather than the other way round — see designing a crate for shipping.
• Air freight is built onto units before it reaches the aircraft, and which piece goes on which unit is its own sequence — see building a ULD for mixed cargo.
• If your question is a number rather than an arrangement, start with pallet counts or loading metres.
• If you want the product mechanics rather than the concept, creating a load plan walks the four steps with screenshots.

What changes next depends on what you do for a living. The same plan is worth different things to a freight forwarder, who is consolidating other people’s cargo and quoting against it, than it is to a manufacturer shipping their own product to a schedule.