Cartonization

Every other split strategy answers how many parcels. This one answers which carton, and what goes in it: the question that decides the invoice, because a carrier bills the greater of what a box weighs and what it takes up.

Switch it on by setting Split strategy → Fit into a real box on a packaging rule.

Every parcel gets a container, whatever the strategy

The strategy above decides how boxes are chosen. A parcel with no container at all has no tare, no volumetric weight, nothing to check a carrier limit against and nothing to draw on the packing table, so every proposed parcel is given one, including parcels produced by a weight split, which name no articles.

Four possible answers, and they are not the same thing:

Answer	Meaning
a fitted carton	the smallest one the goods actually fit
the largest carton	nothing fits: goods stick out, and the plan carries a warning
no carton, on purpose	a single piece the merchant marked own box
no carton, no catalogue	the shop has no packaging materials; one warning is raised, not one per parcel

A parcel deliberately without a carton is still shown at the bench: its goods stand in their place on the row with the box number above them, and no walls around them.

How a box is chosen

1. Each ordered piece is weighed as its own weight plus its packaging per unit. Two cans carry two sleeves; the carton around them is counted once.
2. Anything marked own box is taken out first. A drum does not go into a carton, and treating it as if it might sends the packer looking for a box that does not exist.
3. The rest are sorted largest first and dropped into bins, measured against the roomiest carton in the catalogue.
4. Each bin is then shrunk to the smallest carton that still holds it.

That last step is what reduces cost. Committing to a box when the first item goes in discards the common case in which the last item turns out to fit a size down.

What the fit check actually is

Volume, plus the longest edge, plus the payload limit. It is not a proof that the pieces can be arranged inside the box: genuine three-dimensional packing is a computationally hard problem, and every mid-market system approximates it.

The difference here is that the plan states this. Every cartonized plan carries the warning that the box choice is an estimate; a packer who cannot close it takes the next size up, and the estimate-versus-scale report learns from the miss.

Volumetric weight

A carrier charges for a big light box by volume: length × width × height in centimetres, divided by the carrier’s divisor, 5000 on most European parcel networks. Stockly stores both numbers on the parcel, the real one and the volumetric one, because the merchant checking an invoice needs to see which of the two was billed.

The divisor is a property of the carrier, supplied by the shipping module. No packaging rule can override it: how a carrier turns volume into money is part of its tariff, not a setting in the shop.

When the data is not there

This is the case in most shops, most of the time. Nothing here fails silently:

Situation	What happens
No packaging materials at all	falls back to the weight split, and the plan says why
No article in the order is measured	falls back to the weight split, and the plan says why
Some articles measured	those are fitted; the others get a parcel of their own and are named in a warning
An item bigger than every carton	still gets a parcel, with a warning to pick a box by hand
A carton’s payload runs out before its volume	a second box opens

A cartonizer that answers confidently when no dimensions were filled in is worse than none at all: “one box for everything” is indistinguishable from success until a courier reweighs it.

What ends up on the parcel

• the material it was fitted into, so that it can later be checked whether the right sizes are being purchased
• the volumetric weight beside the real one
• the predicted weight, frozen at creation and never changed again; the gap between it and what the scale says is what reveals an incorrect catalogue entry

What to do next

• Packing data coverage — what still has to be filled in
• Packaging rules — where the strategy is chosen