Why the obvious pattern is usually not the best one
Most people work out cartons per layer by dividing the pallet length by the carton length and the pallet width by the carton width, then multiplying. That is a grid, and it is one of at least two grids available, because the carton can also be turned ninety degrees. On a 48 by 40 pallet a 16 by 11 carton gives three across by three deep in one direction, which is nine, and four across by two deep in the other, which is eight. Nine looks like the answer.
It is not. Lay a bottom band of four cartons turned sideways, occupying 44 by 16 inches of the deck, then fill the remaining 48 by 24 inches with a three by two grid the other way up, and you have ten. The same carton, the same pallet, one more unit per layer. Over six layers that is six extra cartons per pallet, and over a forty pallet order it is 240 cartons that never needed a pallet of their own.
This planner searches plain grids in both orientations and then a family of mixed block patterns, of which the pinwheel is the best known. It reports the best it found and shows you the blocks so you can see whether the pattern is buildable. The search is not exhaustive. Pallet loading is a hard packing problem and there is no quick method that guarantees the true maximum, so treat a result as a good pattern rather than a proven optimum. If you find something better on the floor, the floor wins.
The four numbers that set the load
| Constraint | Where it comes from | What happens when it binds |
|---|---|---|
| Footprint | Deck size and whether overhang is allowed | Sets cartons per layer, and nothing else changes it |
| Height | Trailer or container interior, racking, or a customer standard | Sets layers. Leftover height above the top layer is wasted every single pallet |
| Weight | Your own working limit for the pallet and the equipment moving it | Caps the load below what the height allows, leaving air you paid to ship |
| Carton strength | The board grade and how the columns line up | Not modelled here at all — see below |
When weight binds before height does, the planner says so. That situation is common with dense product and it means the pallet ships partly empty by volume, which is a signal to look at a shorter, denser pattern or a different handling unit rather than to keep stacking.
Compression is the constraint this does not model
A carton carries load through its vertical corners. Stack cartons so the corners line up in continuous columns and the stack is strong. Interlock the layers, which is what a mixed pattern encourages, and the corners no longer line up, and the stack of the same cartons carries considerably less. That is the trade: interlocking resists sliding and column stacking resists crushing, and you rarely get both.
Nothing here calculates whether your carton survives the layers above it. That depends on the board specification, the humidity it will sit in, how long it will sit, and whether the load is racked or floor stacked. If cartons on the bottom layer are arriving crushed, the answer is in the box specification and the stacking pattern together, not in the layer count.
What to hand to whoever builds the pallet
A pattern is only useful if it is repeatable. Write down the carton orientation, the number in each block, the block positions, the layer count, and whether layers rotate. If the pattern is mixed, expect it to be built more slowly and to be miscounted more often than a plain grid, and price that in. Plenty of operations knowingly ship a nine when a ten exists, because the ten costs more in handling errors than it saves in freight.
Once the pallet is built the next questions are how many fit the trailer and what the shipment weighs per cubic foot. Those are the container loading calculator and the freight density calculator. If you are shipping single cartons rather than pallets, the dimensional weight calculator is the one that matters.
Questions people ask
What does "tie and high" mean and does this give me one?
Tie is the number of cartons in one layer and high is the number of layers, so a pattern described as 10 by 6 is ten cartons per layer stacked six layers deep, sixty to the pallet. This planner gives you both numbers along with the arrangement that produced the tie, which is the part a bare "10 by 6" leaves out. Two different patterns can both be a tie of ten and only one of them may be buildable with your carton. That is why the block breakdown is shown rather than just the count.
Should I let the load overhang the pallet?
It buys footprint and costs you in three places, so it is a judgement rather than a rule. Overhanging cartons lose the edge support of the deck underneath, which is exactly where a carton carries its load, so column strength drops. The load is more exposed to damage from other freight and from forks. And for freight purposes the shipment is measured to its widest point, so an overhanging load is dimensioned as if the pallet were that size anyway, which cancels part of the saving. Set the overhang field to what you are actually considering and look at what it does to the layer count before deciding.
Why does the mixed pattern fit more than the grid?
Because a grid wastes whatever is left over on two edges, and a mixed pattern uses one of those leftovers by turning cartons to suit it. On a 48 inch deck a 16 inch carton leaves nothing over, but on the 40 inch dimension an 11 inch carton leaves 7 inches, which is dead space in every row. Turn a band of cartons so the 11 inch dimension runs along the 48 inch side and four fit with 4 inches over, and that band now occupies only 16 inches of the 40, leaving a clean 24 for a different grid. The gain is always in reclaiming an edge remainder, which is why patterns with a small remainder gain nothing and patterns with a large one can gain a lot.
Can I stack pallets on top of each other?
That is double stacking and it is a question about the product, the carton and the receiving operation rather than about geometry. The bottom pallet carries the whole weight of the top one through its own top layer of cartons, which is the layer least designed for it. Many shipments are marked as not double stackable for exactly that reason, and a load that arrives double stacked when it was not meant to be is a damage claim. If you are planning around it, the height limit field is where you enter the height of one pallet and the trailer question belongs in the container calculator.
Does the pallet weight matter if I am shipping by weight?
Yes, and it is the number people leave out. A wooden pallet is commonly somewhere between thirty and seventy pounds depending on the type and how wet it is, and that weight is part of the gross that gets billed and part of the load your equipment lifts. On a pallet holding sixty cartons of fourteen pounds each, a fifty pound pallet is about six percent of the gross. Put the actual weight of the pallet you use into the field rather than leaving it at the default, because the type varies and so does the number.