Box in a box: how many cartons fit in a master case
Enter the inner size of the master case and the outer size of the carton going into it — the calculator tries all six orientations and works out an orthogonal pack, the way a warehouse actually loads. Up to four different carton sizes at once. Inches, free, no sign-up.
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Give the master case its inner dimensions and the carton its outer ones. If you only have the outer size of the master case, switch the mode and enter the wall thickness — single wall corrugated runs about an eighth of an inch, so two layers take a quarter inch off each dimension.
The gap field adds clearance around every carton. Leave it at zero for a tight pack, or put in a sixteenth or an eighth if the cartons bulge or you want the case to close easily.
What it does differently
All six orientations
A carton can go into a case six ways, and the count often changes a lot between them. Most calculators try one. This one tries all six and shows which way wins, plus the full list so you can pick a different orientation if the product will not lie on its side.
Orthogonal packing, not volume division
Dividing case volume by carton volume gives a number that never happens in real life. This works out an actual grid — so many across, so many deep, so many layers — which is what your packers will build.
Up to four carton sizes
Mixed cases are normal in retail. Type one takes the best block, and the rest fill what is left. The layout section shows where each type ended up.
Common carton sizes
| Carton | Inches | Typical use |
|---|---|---|
| Large moving | 24 × 18 × 18 | Bulky light goods, linens |
| Cube | 20 × 20 × 20 | General master case |
| Medium | 18 × 18 × 16 | Mixed retail packs |
| Standard cube | 16 × 16 × 16 | Ecommerce master case |
| Small cube | 12 × 12 × 12 | Inner cartons, samples |
| Mailer | 8 × 8 × 8 | Single units |
Carton specs usually quote inner dimensions. Outer size is larger by two wall thicknesses on each axis — worth checking before you order a run.
FAQ
Why does the answer change when I rotate the carton?
Because the case is not a cube, and neither is the carton. Turning it changes how many fit across and how many layers you get. Sometimes a worse-looking orientation fits two more.
Should I enter inner or outer dimensions?
Inner for the master case, outer for the carton going in. The calculator can convert the master case from outer to inner if you give it the wall thickness.
Why is my real count lower than the calculator?
Usually bulge or dunnage. Cartons packed full swell at the sides, and void fill takes room. Put an eighth of an inch in the gap field and the number will come closer.
Does it account for weight limits?
No. It solves geometry only. Check the case's burst or edge crush rating separately — a case that holds 48 units by volume may not hold their weight.
Is my data sent anywhere?
No. The widget runs entirely in your browser — dimensions and results are never transmitted or stored.