Why your pallet holds fewer cartons than the spreadsheet says
Dividing pallet volume by carton volume overstates what fits, often by twenty percent. How real two-block packing works, and what it changes about your freight quote.
Someone in the office does the arithmetic. A Euro pallet is 1.2 by 0.8 metres, stack it 1.65 metres high above the deck, that is 1.584 cubic metres. Each carton is 40 by 30 by 25 centimetres, which is 0.03 cubic metres. Divide one by the other: 52 cartons per pallet.
The warehouse gets 48. Sometimes 44. And the freight quote you built on 52 is now short by a pallet on every second shipment.
The reason is boring and unavoidable
Cartons are rigid. Volume division assumes they are not.
Put 40 by 30 centimetre cartons on a 120 by 80 centimetre deck. Three along the length, two across the width: six per layer, using 120 by 60 centimetres. That leaves a strip 120 by 20 centimetres, and nothing 30 centimetres wide fits into 20 centimetres of space. The strip stays empty.
Six per layer at 25 centimetres tall, with 165 centimetres of usable height, gives six layers. Thirty-six cartons. Volume division promised 52.
You can do better by rotating. Fill the main block one way, then pack the leftover strips with cartons turned ninety degrees. On this pallet, turning the cartons crosswise gives four along the width and two along the length, which uses the deck differently and may leave a usable strip. A good loader tries both and takes the better one, without thinking about it as an algorithm.
That is exactly what our pallet calculator does: it fills the main block in one orientation, packs the two leftover strips in the rotated orientation, and takes the better of the two starting orientations. Because the strips are disjoint by construction, the number it gives you is always physically achievable. It is a floor, never an optimistic guess.
Every free pallet calculator I tested divides volumes.
What binds first, height or weight
The second thing spreadsheets miss is which constraint arrives first.
A Euro pallet is generally rated to about 1,500 kilograms. Cartons weighing 40 kilograms each hit that at 37 cartons, which may be fewer than the height allows. In that case adding height achieves nothing and you need more pallets, not taller ones.
Go the other way — light, bulky goods — and you hit the height limit with the pallet barely loaded, and you are paying to ship air. That is when it is worth asking whether a different carton size would tile the deck better. Dropping a carton from 40 by 30 to 40 by 26.6 centimetres does not sound like much, but it means three fit across an 80 centimetre width instead of two, and the pallet count changes materially.
Redesigning a carton to fit a pallet is one of the highest-return things a growing ecommerce business can do, and almost nobody does it, because the carton was specified once by whoever set up the product and never revisited.
Containers make the same mistake, larger
A 40 foot high cube holds about 76 cubic metres. Divide that by carton volume and you get a number nobody can achieve.
Loose loading — cartons stacked directly on the container floor — typically fits 10 to 15% more than palletised, because pallets waste both floor area and 14 centimetres of height each. But palletised loads and unloads far faster, damages less, and is sometimes mandatory at the receiving warehouse. If your destination charges by the hour to unload, palletised often wins on total cost despite fitting less.
There is one constraint people forget: the door. A 40 foot high cube has an internal height of about 269 centimetres but a door opening of about 258. A pallet built to the internal height does not go in. Our container load calculator uses the door height for palletised loads for exactly this reason.
Then there is the last container. If you are shipping 800 cartons and 620 fit in a 40 high cube, your second container is 29% full and you are paying full freight for it. Comparing that against sending the balance as LCL is usually worth ten minutes, and it is the sort of decision that never gets made because nobody surfaces the remainder.
The other reason to get this right
Freight class, if you are shipping LTL in the United States.
Class comes from density: pounds per cubic foot, using the pallet as loaded. Pack tighter and density goes up, class goes down, and the rate falls. The break points are real and close together — at 9 to 10.5 pounds per cubic foot you are class 100, and at 10.5 to 12 you are class 92.5.
NMFTA replaced the tier structure with a 13-tier density scale in July 2025 and reclassified over 2,000 commodity codes, so a calculator still running the older chart will misclassify some shipments. Our freight class calculator uses the current scale and tells you how far you are from the next break, which is occasionally the difference between packing tighter and renegotiating a contract.
Worth saying plainly: density is only one of four NMFC factors. Stowability, handling and liability can all move a class regardless of how dense the pallet is, and carriers reweigh as routine. Treat any class you calculate as your opening position, not a settled fact.
The short version
Measure the pallet as loaded, including overhang and the pallet itself. Check whether height or weight binds first. Try both carton orientations before accepting a layer count. Look at what the last pallet and the last container are costing you. And if you are specifying a new carton, specify it against the pallet you actually ship on rather than against the product.
None of this is sophisticated. It is just arithmetic that a volume division quietly skips.
Sending the pallet manifest on to a forwarder? ToolsBay, our sister site, renders a packing-list spreadsheet as a paginated PDF in the browser, without uploading the file anywhere.