A pallet layout calculation answers how many cartons fit a stated footprint and height; the shipment still needs a suitable pallet, cartons and securing method. Begin with the real external carton dimensions and usable pallet deck, compare the two simple orientations, and then limit the stack using the actual height and load conditions.
For cable gland orders, a small carton can contain substantial metal mass. A layout that fits neatly may reach a weight or carton-compression limit before it reaches the transport height limit. The worked example below keeps those checks visible without treating a geometric result as a packing approval.
Define the usable deck and permitted carton orientation
Record pallet length and width, carton external length, width and height, and whether the carton may rotate on its base. Turning a box through 90 degrees on the pallet is different from laying it on its side. Keep the approved upright face unchanged unless the packaging instructions permit another orientation.
Use dimensions of the closed, filled carton. Include normal bulging, closures and dimensional variation where they affect fit. Internal box dimensions describe storage space and should not be used to calculate the outside packing footprint.
The example assumes a 1,200 × 1,000 mm usable deck and identical 450 × 300 × 250 mm cartons, with both upright base orientations allowed. It assumes no overhang and initially no inter-carton gaps. These are declared calculation inputs, not a standard pallet or box specification for all cable gland shipments.
FedEx’s pallet-packing guidance advises keeping products within the pallet edges and selecting a pallet strong enough for the load. The applicable carrier and warehouse requirements set the real usable dimensions before you count rows.
Compare the two complete rectangular grids
Let the usable deck be by and the carton base be by , all in the same unit. For uniform rows with no gaps:
The first layout gives 2 × 3 = 6 cartons per layer. Rotating every carton on its base gives 4 × 2 = 8 cartons per layer. For our comparison of these two candidate grids, we can carry the eight-carton arrangement forward for further investigation.
This tool does not search every possible arrangement. Mixed orientations, interlocking patterns, gaps and irregular loads can change the result. Calling the larger of these two grids the global optimum would overstate the calculation. You can use a packing-layout tool or a physical trial when a mixed pattern is worth evaluating.
The drawing shows the exact geometric relationship used in this example. Its unused bands are visible so you can see where nominal spare space remains; that spare space must be considered in the actual securing design.
Recheck clearances before accepting the count
The rotated example fills all 1,200 mm along one deck direction: four cartons at 300 mm each. That leaves no allowance in that direction for dimensional growth or gaps. I would flag this result as sensitive to the measured carton width rather than assume the nominal row will fit.
If the filled width becomes 302 mm, four cartons need 1,208 mm. The eight-carton grid no longer meets the stated no-overhang condition. Re-enter the actual dimensions; do not squeeze the row or omit protection to preserve the previous count.
Where a gap is required between adjacent cartons, a row of cartons of width consumes . Reserve edge allowances separately. The simple calculator does not include these gaps, so the final drawing must show them explicitly or use appropriately reduced usable dimensions with a justified placement scheme.
Check pallet deck openings and carton support as well as outline fit. A carton positioned within the perimeter can still be poorly supported by the deck. The useful result is an arrangement you can physically reproduce with the specified filled boxes and protection.
Limit layers by height, mass and carton performance
For a maximum overall shipment height , pallet height , total additional height allowance and carton height , a preliminary height limit is:
The allowance must include the actual top protection and any interlayer materials. If their thickness changes with the number of layers, solve using that layer-dependent total instead of a fixed value. A non-positive available height cannot accommodate a layer.
With a 1,400 mm overall limit, a 150 mm pallet, 50 mm total reserved allowance and 250 mm cartons, the result is four layers. Five layers would require 1,450 mm with these same allowances and would exceed the limit.
At eight cartons per layer, four layers contain 32 cartons. Suppose each filled carton has a gross mass of 12 kg, the pallet weighs 25 kg and other securing material weighs 5 kg. The fully packed pallet would weigh 414 kg, including 389 kg above the pallet. Compare the correct quantity with each limit: a pallet payload rating and a handling-unit gross limit need not have the same boundary.
Height and mass are still insufficient to establish the carton stacking limit. Ask for packaging evidence representing the filled carton, load duration, environment and stacking pattern. If the approved packaging arrangement permits only three layers, use three even though four fit geometrically. FedEx distinguishes column stacking from interlocking arrangements; the choice affects both support and load stability. It should follow the contents and packaging design rather than a preference for a visually tidy pattern.
Reconcile full pallets and the final partial pallet
Once the actual packing arrangement permits 32 cartons per pallet, an order of 75 cartons requires:
- Two full pallets, carrying 64 cartons together.
- One partial pallet, carrying the remaining 11 cartons.
- Three pallets in the shipment, with 75 cartons rather than a theoretical capacity of 96.
Keep pallet capacity and actual loaded quantity in separate worksheet columns. Multiplying cartons per layer by layers and pallet count gives total capacity only when every stated layer and pallet is filled as assumed.
The partial pallet needs its own layer arrangement, securing method, external dimensions and gross mass. Eleven cartons do not automatically form a stable stack by copying the first 11 positions from a full-pallet drawing. Depending on the approved packaging method, spreading the remainder differently or using a smaller suitable base may be preferable. Recheck handling access and carrier acceptance after any change.
Confirm the finished handling unit
Before the layout is released for dispatch, reconcile the physical load with the drawing: actual carton count and identities, orientation, support, occupied footprint, height, gross mass, restraint and label visibility. Record the final dimensions after wrapping, since they are the dimensions tendered for transport.
ISO 780:2015 covers graphical handling instructions on distribution packages. Follow the relevant marked orientation and stacking instructions; the presence of a symbol does not supply a missing load rating.
A freight quotation should describe the actual handling units, including any stacking restriction. For the broader commercial comparison, the CW gland quotation guide shows why equivalent packaging and delivery boundaries matter. I would compare shipment offers only after both suppliers have described the same packing basis.
Conclusion
Pallet geometry identifies a workable candidate layout; the physical conditions can then reduce its capacity. In the example, rotating the cartons changes the simple layer count from six to eight. Height, support, weight and approved stacking conditions determine whether those eight-carton layers can become a usable shipment.
Keep the final partial pallet visible in the record. A repeatable packing plan describes the cartons actually loaded, their measured envelope and the chosen restraint; it does not stop at the maximum capacity of a rectangular grid.
FAQ
Does the calculator find the maximum possible cartons per layer?
It compares two complete rectangular grids, one with every carton rotated by 90 degrees. It does not search mixed orientations or irregular packing patterns. I treat the higher count as the better of those two candidates and review an alternative arrangement separately when the potential improvement justifies the additional packing complexity.
Can I reduce carton height by putting boxes on their side?
Only when the approved packaging and handling instructions allow that orientation. Rotating a carton on its base preserves its upright direction; laying it on its side changes the loaded faces and product orientation. I would obtain a suitable packing arrangement for that position before using its shorter dimension as the stack height.
Why can a nominally exact four-carton row fail to fit?
Nominal dimensions may omit filled-carton bulging, closures, protection, dimensional variation or required gaps. Four nominal 300 mm cartons fit exactly within 1,200 mm, but four cartons measuring 302 mm need 1,208 mm. Use actual external dimensions and the required allowances rather than treating an exact nominal fit as guaranteed clearance.
Does a pallet’s load rating establish the carton stacking limit?
No. The pallet supports the load, while the bottom cartons must also withstand the applicable stacking arrangement and conditions. Carton compression, load duration, environment, product support and restraint remain separate considerations. I select the permitted layer count from the relevant packing evidence as well as the height and handling-unit mass limits.
Sources and technical references
- FedEx — How to ship using pallets, accessed 2026-10-22.
- SIS — ISO 780:2015: Distribution packaging handling and storage symbols, accessed 2026-10-23.