How the regular-grid estimate works
The calculator tests six rotations of an identical rectangular item. For each rotation it divides the carton’s internal length, width and height by the padded item dimensions, rounds each count down, and multiplies the three counts. It reports the rotation with the highest count.
Items per carton = floor(L ÷ l) × floor(W ÷ w) × floor(H ÷ h)
Cartons needed = round up(order quantity ÷ items per carton)
Worked example
A carton with 40 × 30 × 20 cm of usable space and a 10 × 8 × 5 cm item needs a clearance decision. With 0.5 cm on every side, the effective item size becomes 11 × 9 × 6 cm. The 11 × 6 × 9 orientation fits 3 × 5 × 2 items, or 30 per carton. An order of 50 therefore needs at least two cartons under this model.
The grid numbers follow the carton’s length, width and height, in that order. Product-volume utilization divides the volume of the unpacked products in a full carton by the carton’s interior volume. It excludes the clearance material, so it is not a measurement of physical empty space.
The limits matter
This is not an optimal 3D packing solver. All items in a calculated carton share one orientation, so a mixed-orientation arrangement might fit more. There is no diagonal placement, nesting, compression, load-bearing model or maximum-weight constraint. Fragile products and products that must stay upright need additional checks. This version allows all six rotations; do not use a sideways layout for a product that cannot safely be turned.
Before ordering cartons
Try the layout with a sample carton, your real product and the actual protective materials. Check that the flaps close without pressure and that the complete parcel stays within the packaging and carrier limits. Use inner dimensions for fit and outer dimensions for shipping.
Common questions
Why can an item fail to fit when its volume is smaller?
Volume does not capture shape. A long, narrow item can have a small volume and still exceed every usable side of a carton.
What does zero clearance mean?
It assumes a perfect geometric fit without room for wrapping, tolerance or handling. That is useful for checking arithmetic, but it is not a packing recommendation.
Does this handle different products in one order?
No. It models identical rectangular items. For mixed products, make a physical layout or use a dedicated multi-item packing tool.