Count the walls, not just the bottles
A partition grid n cells wide has n plus 1 walls across it, because there is one against each side of the box as well as one between each pair of containers. Four cells is five walls. At sixty thousandths of an inch a wall that is three tenths of an inch of the case width gone before a single bottle goes in, and it is almost always the difference between an arrangement that works and one that does not.
The arithmetic below is what the calculator does in each direction. It is worth being able to do it in your head at the supplier, because the answer changes the box you order.
| Quantity | How it is worked out |
|---|---|
| Pitch of one cell | Container footprint, plus clearance, plus one wall |
| Cells that fit a span | The span less one wall, divided by the pitch, rounded down |
| Space actually used | Cells times footprint and clearance, plus one more wall than there are cells |
| Slack | Whatever is left, which is board and freight you are paying for |
Clearance is a labour decision
With no clearance at all, a bottle has to be lowered exactly straight into its cell or it catches. By hand that is slow, and it is slow on every unit for the life of the product. With a little clearance the bottle drops in. The cost is that the arrangement may lose a column, so the trade is a real one: fifty thousandths per container across four cells is two tenths of an inch, which sometimes matters and often does not. Try it both ways on this page before deciding.
Where the case goes next
Once you know the outside dimensions and the gross weight, the case becomes a carton and the rest of the chain has its own pages. Layers and orientations on a pallet are the pallet load planner. Pallets or loose cartons into a trailer or a container are the container loading calculator. If you are shipping single cases by parcel, the billable weight comes from the parcel volume and dimensional weight calculator, and pounds per cubic foot for a freight class comes from the freight density calculator. Empty space inside the case that wants filling is the void fill calculator.
What this page will not tell you
It has no opinion about whether a stack is safe, how high anything may be stacked, or whether a container survives being at the bottom of two tiers. A filled case is much heavier than an empty one and a filled pallet is heavier again; the stacking height is a load question for the racking and the floor. Glass breaks under loads it did not break under empty. And it states no rule about how a shipped package must be marked or declared — that comes from the agency and the carrier, not from here.
Questions people ask
Why does my box hold fewer bottles than the raw division suggests?
Dividers, almost always. A grid four cells wide has five walls, not four, and each of those walls is real material. Add the clearance you left around each container and the two together commonly eat half an inch across a case, which is enough to lose a column. Work it as cells and walls rather than as a division and the answer stops being a surprise.
Should I leave clearance around each container?
It is a trade between packing speed and case size. With none, every bottle has to go in perfectly straight or it catches on the divider, and by hand that cost repeats on every unit forever. With some, packing is quick and you may lose a column. Fifty thousandths per container is a common compromise. Run it both ways here and see whether the arrangement actually changes.
Does it handle bottles that are not round?
Yes. Choose the rectangular footprint and give it both sides, and it tries the layout in both orientations and keeps whichever fits more. It tells you which one it used and how many the other would have held, which is worth seeing when the two are close.
What weight should I use for a filled container?
A weighed one. Glass varies more than you would expect between moulds, and the product weight depends on its density rather than its volume. Put one filled and capped container on a scale. Estimating it is how a case weight ends up a third out, and case weight is the number everything downstream is built on.
Can I stack two tiers inside the case?
The arithmetic will do it if the inside height allows, but whether the container takes it is not an arithmetic question. The lower tier carries the upper one for the whole journey, and a filled case is far heavier than an empty one. That is a question for whoever makes the container and the closure.