Planning a container load: pallets, weight and volume

Loading a container looks like a sum of pallets and metres, but you are managing three limits at once: floor area, height and weight. The first two are visible to the eye. The third only shows when someone adds up the pallets, and by then the load has often been ordered, picked or even sent to the port.

Rules of thumb by container type

Treat these as ranges, not promises. Inner dimensions differ by a few centimetres between container builders and shipping lines, and the exact count depends on the pallets themselves: cartons overhanging the edge, a bent pallet, how much room you leave at the doors. A high cube is about 30 cm taller, but not bigger on the floor. That is why it adds nothing in a single layer. The extra height only matters for pallets taller than about 1.1 m and lower than about 1.25 m: those fit in two layers in a high cube, but not in a standard container.

Space or weight

For most containers the maximum payload sits roughly between 26 and 28 tonnes, depending on the type and the shipping line. A pallet of crisps or biscuits weighs a few hundred kilos and fills the space long before weight matters. A pallet of drinks, cans, oil or sugar often weighs 1,000 kg or more. At 1,200 kg a pallet, 24 pallets come to 28,800 kg, more than a 40ft container may carry, while there is still floor space left. For light goods, volume is the limit instead: the inner volume is about 33 m³ for a 20ft, about 67 m³ for a 40ft and about 76 m³ for a 40ft high cube, and it can be full before weight or floor area becomes the constraint.

Whether space or weight sets the limit depends mostly on these points:

• Weight per pallet: drinks, cans, oil, sugar and preserves are heavy, snacks and packaging are light.
• The maximum payload of the container and the terms of the shipping line.
• Road transport: the maximum gross weight on the road differs per country and can be lower than what the container itself allows.
• Weight distribution: heavy pallets belong spread across the floor, not all at the front or the back.
• Verified gross mass (VGM): it has to be declared before the container is shipped, and it can only be right if the plan is right.

Rotating and stacking

A europallet measures 1200 by 800 mm, an industrial pallet 1200 by 1000 mm. By placing some pallets lengthwise and some across, you use the width of about 2.35 m better than with a single orientation. That is often worth one or two pallets per container. It only pays off if the position at the doors and the gap to the walls are right.

Stacking works only if the pallets are stackable: sturdy packaging, no overhang and a bottom layer that carries the weight. The door opening is lower than the inner height, so in a standard container count on roughly 1.1 m per layer including the pallet, and in a high cube on about 1.25 m. If you do not have pallet height in your product data, you are guessing.

Mixed loads

A mixed load combines pallets of different height and weight with cartons loaded by hand to fill the leftover space. Heavy goes at the bottom and light on top, and when there are several receivers the unloading order decides how you load. A refrigerated container has a smaller loading space than a dry one because of the cooling unit and the airflow, so the table above does not apply to it.

Why plan before loading

A mistake in the load costs the most at the end: pallets that go back to the warehouse, an extra container, or a container that leaves half empty. Planning when the order comes in, not on loading day, avoids that. Then you can still adjust quantities, merge pallets or choose another container type.

Calculating by hand works for a single standard load. Once products differ in size, weight and stackability, a planner that knows those details helps. BDI Nexus builds such planners: 20ft, 40ft and refrigerated loads with pallets and hand-loaded cartons, in 3D, on the product data you already have. You see at once whether the container is full on space or on weight.