How this calculation works
A pallet layer is a two-dimensional packing problem before it is a stack. Turning some rectangular cartons can fill a strip that a single orientation leaves empty. The diagram shows the actual arrangement chosen by this restricted search, rather than an area ratio that assumes every square millimetre can be used.
Layer count = best of two-zone rectangular layouts; layers = floor((overall height − pallet height)/carton height); allowed count = min(layer count × layers, floor((gross ceiling − tare)/carton mass))A worked example
On a 1200 by 1000 mm footprint, 400 by 300 mm cartons can occupy ten places in the two-zone layer. With a 150 mm pallet inside an 1150 mm overall height, four 250 mm carton layers fit. Forty cartons at 10 kg plus 20 kg tare weigh 420 kg. Lowering the entered gross ceiling to 315 kg permits only 29 cartons, even though the height and layer arrangement have not changed.
Good to know
Two-zone 90-degree packing heuristic only; no global packing optimality, overhang, compression or transport approval. If tare alone exceeds the mass ceiling, zero cartons is the arithmetic result but the empty pallet still exceeds the entered ceiling. Check the gross-mass metric rather than interpreting zero as a compliant load.
Reference: OpenStax — right-triangle trigonometry (opens in a new tab) ↗
What this model answers
A pallet layer is a two-dimensional packing problem before it is a stack. Turning some rectangular cartons can fill a strip that a single orientation leaves empty. The diagram shows the actual arrangement chosen by this restricted search, rather than an area ratio that assumes every square millimetre can be used.
The search compares two rectangular zones with perpendicular carton orientations, and also tries a transposed split. It does not enumerate every possible interlocking layout. Its count is an achievable geometric arrangement within this model, not a proof that another arrangement cannot hold more.
The Shipping container carton packing calculator extends the geometry question to three interior dimensions and a door cross-section. Pallet tare and pallet height must be included separately when a real shipment uses pallets.
Measure the right inputs
Measure the loaded carton dimensions including bulges, not just the flat box specification. Edge clearance is removed twice from each pallet dimension; the inter-carton gap applies only between neighboring cartons inside the chosen layout.
Enter the total permitted height including the pallet itself. If only cargo height is available in a specification, add the pallet height before using that ceiling. The mass ceiling also includes empty pallet tare, so gross capacity and cargo-only capacity are different inputs.
Read the result in context
The layout plot draws up to eighty cartons so a dense grid stays usable. The headline count and zone table still include every modeled carton. A mass-limited final count may stop part-way through the last geometric layer; the plot represents a layer pattern rather than the finished stack.
A carton that fits geometrically may still be unsuitable underneath other cartons. Compression strength, interlayer sheets, restraint, uneven support and load movement are separate checks. An entered rating is a planning assumption and is not validated against a pallet manufacturer or carrier.
Work through the numbers
On a 1200 by 1000 mm footprint, 400 by 300 mm cartons can occupy ten places in the two-zone layer. With a 150 mm pallet inside an 1150 mm overall height, four 250 mm carton layers fit.
Forty cartons at 10 kg plus 20 kg tare weigh 420 kg. Lowering the entered gross ceiling to 315 kg permits only 29 cartons, even though the height and layer arrangement have not changed.
Where the model stops
Two-zone 90-degree packing heuristic only; no global packing optimality, overhang, compression or transport approval.
If tare alone exceeds the mass ceiling, zero cartons is the arithmetic result but the empty pallet still exceeds the entered ceiling. Check the gross-mass metric rather than interpreting zero as a compliant load.
A few questions, answered
Why not divide pallet area by carton area?
An area quotient is only an upper bound and ignores edges, gaps and whether whole rectangles can actually be arranged.
Can the last layer be partial?
Yes. The mass clamp can leave a partial final layer; arranging and restraining that partial layer is outside this model.