Packaging comes in levels, and a master carton is the outermost one that still belongs to you rather than to the freight company. It is the case that arrives at a warehouse, gets scanned, gets stacked on a pallet and gets opened by someone replenishing a shelf. Get it wrong and the cost lands on every unit you ship.
The three levels
| Level | Usual name | What it does |
|---|---|---|
| Primary | Retail unit | Holds the product, carries the brand and the consumer facing information |
| Secondary | Inner carton or display | Groups retail units into a replenishment quantity, sometimes doubling as a shelf tray |
| Tertiary | Master carton or shipper | Protects the lot in transit, carries the case marks and stacks on a pallet |
Not every product needs all three. Small, fast moving items usually justify an inner because it makes replenishment quicker. Large items often go straight from retail unit to master carton.
The four numbers to decide
Units per inner and inners per master are commercial decisions as much as packaging ones, because they set the quantity a retailer has to buy and the quantity a picker has to handle. Master external dimensions follow from those counts and from how the units tile inside. Master gross weight follows from the contents. Ask your 3PL or retailer for their maximum carton weight and maximum carton dimensions and treat both as hard limits, because a case that exceeds them gets rejected or surcharged.
What goes on the outside
A master carton needs to be readable in a warehouse aisle by someone who is not looking for it. Plan for the product description and SKU, the quantity inside, the carton number in the sequence, lot or batch information if you have it, and any handling marks the contents demand. Case level barcodes normally use ITF-14, the GS1 symbology intended for cartons, which is printed larger and tolerates the rougher print surface of corrugated better than a retail symbol does. Goods imported into the United States also carry country of origin marking requirements, so confirm the mark with your customs broker before the artwork is finalised.
Make it fit the pallet
The standard pallet in North American grocery and general merchandise is 48 x 40 in. Work out how your carton footprint tiles onto that area. A carton that leaves four inches of unused deck on every layer wastes that space for the life of the SKU, and a carton that overhangs the pallet edge loses most of its stacking strength, because the corners are no longer supported. Adjusting the master carton by half an inch to tile cleanly is one of the cheapest savings in packaging.
Board and construction
Most masters are regular slotted containers in single or double wall. If the contents are heavy, or the lane is rough, a full overlap gives you two layers of board across the top and bottom, which is explained in full overlap box dimensions. The board grade conversation is covered in what ECT means.
Ordering
Minimum order is 100 boxes, from about $0.48 per unit at bulk volumes, confirmed on your written quote. Die and plates, design support, US shipping and a digital proof before anything prints are included. Lanes are Rush (expedited production plus air freight), Standard (air) and Cost saver (sea), from about 7 business days, plus 2 to 5 for delivery, with specialty imported items running up to about 12 weeks. Rush adds about 7 to 25%, depending on the job.
Send your retail unit dimensions and the case counts you want and we will size the master and check it against a 48 x 40 in pallet at /quote/.
