The short answer: the size you need is whatever your load measures, plus clearance, expressed as an internal dimension. There is no catalogue to pick from, because a full overlap box is cut to your die. The useful question is therefore not which size exists, but which constraint decides yours.
Find the constraint that is actually binding
| If this is true | Then this decides the box | What to do |
|---|---|---|
| One product per box, shipped alone | The product | Measure it at its extremes, add clearance for padding, done |
| Cases go out on pallets | The 48 x 40 in pallet footprint | Choose a footprint that tiles into it with little waste |
| Cases ship as individual parcels | Carrier dimensional weight | Cut the empty volume, since air is billed on every parcel |
| Cases sit on a retail shelf | Shelf depth and height | Get the external dimension, not the internal, and check the planogram |
| Mixed items per box | The packing arrangement | Lay the items out as the packer will, then measure the arrangement |
Most operations have exactly one binding constraint. Identify it, size to it, then check the other four do not fail.
Is full overlap even the right style
A full overlap has outer flaps that overlap completely across the top and bottom, giving two thicknesses of board on those faces. Choose it when the box is heavy, when it is handled repeatedly, when the contents shift, or when doubling the two critical faces is cheaper than stepping the whole box up to double wall. Skip it when the load is light and stable and material cost is the priority, because you are buying board area you will not use.
Clearance, in practice
There is no universal clearance figure, because it depends entirely on what sits between the product and the wall. Work it out rather than guess it: take the thickness of your liner, pad, insert or void fill, and add it on both sides of each axis. If nothing sits between the product and the wall, you still want enough room for a human being to get the product in and out at line speed without forcing it. A box that fights the packer is a box that ends up torn.
Internal or external
This single confusion causes more wasted dies than anything else in box buying. State your dimension as internal length x width x depth and write the word internal on the request. Then read the quote back and check the supplier has used the same basis. Board caliper adds roughly two thicknesses per axis, which sounds trivial until it is the difference between fitting a pallet layer and not.
What you get on an iBox order
Minimum order is 100 boxes. Pricing starts from about $0.48 per unit at bulk volumes, confirmed on your written quote. The cutting die and the printing plates are included along with design support, US shipping and a digital proof, which is the reason to ask for the exact size your load needs rather than the nearest convenient one. Three lanes run: rush with expedited production and air freight, standard on air, and cost saver by sea, from about 7 business days, plus 2 to 5 for delivery. We make these in West Chicago and in Guangzhou.
If you would like the full measuring procedure rather than the decision, how to size a full overlap box walks it step by step. When you have the three numbers and the loaded weight, send them through the quote form.
