Mixed pallets: how to build and label a mixed-SKU pallet

A mixed pallet carries more than one product. It is the normal unit in store replenishment, e-commerce fulfillment, LTL shipping and small-order wholesale, and it is harder to build well than a single-product pallet because the cases differ in size, weight and strength. This guide gives practical rules for building a stable mixed pallet and labeling it so the receiver can check it in.

#Types of mixed pallet

A rainbow pallet keeps most of the advantages of a single-SKU pallet: even layers, good column strength, and easy counting. A fully mixed-case pallet is the most flexible and the hardest to stabilize.

If the order allows it, build full layers of each product and mix only the top layer or two. You get a stable, countable pallet and still ship the exact quantities ordered. When an order is too small for full layers, consider whether two single-SKU half-height pallets, or a single-SKU pallet plus a small mixed pallet, would travel better than one tall, fully mixed load.

#The build order: heavy, strong and square first

Think of a mixed pallet as a wall, built from the bottom up.

1. Base layer: heaviest, strongest, most regular cases. Liquids in cases, canned goods, dense boxed goods. They make a flat, stiff foundation and keep the center of gravity low.
2. Middle layers: medium weight and strength, grouped by case size so each layer is as flat and square as possible.
3. Top layers: light, fragile and irregular items. Anything that would crush under weight goes last.
4. Fill voids with dunnage, void fill or empty cartons so upper cases are fully supported.
5. Cap and wrap. A top sheet or corner boards plus tight stretch wrap anchored to the pallet.

#Keep layers flat

Every uneven layer weakens the layers above it, because cases bridge across gaps and lose their column strength. Group cases of the same height together, and use a tier sheet (a sheet of corrugated or plastic) on top of an uneven layer to give the next layer a flat surface. See pallet stacking patterns.

#Balance the load

• Keep the heaviest cases in the center of the pallet rather than at one edge.
• Aim for a center of gravity near the middle of the footprint and as low as possible.
• Build to the edges of the pallet but not past them. See pallet overhang.
• Keep the top flat if the pallet may be double stacked; cone or mark it "do not stack" if not.

#Compatibility rules

Some products must not share a pallet, or must be separated on it.

• Food and chemicals: never put cleaning products, fuels or other chemicals above food. Many shippers keep them on separate pallets.
• Allergens: separate or seal products where cross-contact is a concern.
• Liquids: place low, upright, and away from paper goods and electronics.
• Temperature: do not mix frozen, chilled and ambient products on one pallet unless the whole pallet goes at the colder temperature and the warmer products tolerate it.
• Hazardous materials: follow the hazmat segregation and marking rules for the mode of transport; some classes cannot be loaded together.
• Odor: strong-smelling products can taint food and packaging.

#Labeling a mixed pallet

A mixed pallet gets one pallet-level label and every case keeps its own product identification.

• Pallet label: a GS1 logistic label with its own SSCC, on two adjacent sides. On a mixed pallet the label usually carries the SSCC and address data but no single product GTIN. See pallet labels and SSCC.
• Case labels: each case shows its own GTIN barcode, and often lot and date information.
• Advance ship notice (ASN): lists each SSCC and every SKU and quantity on that pallet. The receiver scans the pallet and checks the ASN rather than counting every case.
• "Mixed" marking: some receivers ask for a visible "mixed pallet" or "mixed SKU" marking. Check the vendor guide.

Retailers set their own mixed pallet rules. Some require single-SKU pallets for certain programs, limit the number of SKUs per pallet, or require products to be grouped by SKU within the pallet. See the retailer pages for Amazon, Walmart and Costco, and always check the current guide.

#Picking and building in the warehouse

Mixed-case pallets are usually built by pick order. A good warehouse system sequences picks so heavy, strong cases are picked first and fragile ones last. Where volumes justify it, mixed-case palletizing robots build the pallet in a planned sequence from a 3D pattern. Both depend on accurate case dimensions and weights in the item master.

Practical rules for manual builds:

• Stage cases by size and weight before building.
• Build one flat layer at a time.
• Check height as you go against the maximum for the trailer, rack or customer.
• Photograph the finished pallet with its label for claims and disputes.

#The pallet under a mixed load

Mixed loads stress the pallet unevenly. Heavy cases on one side load one stringer or row of blocks more than the others, and small cases can sag into wide deckboard gaps. For mixed loads:

• choose a pallet with closer deckboard spacing or a tier sheet on the deck (see deckboard thickness and spacing);
• use a four-way pallet if it will be cross-docked;
• avoid damaged recycled pallets, which fail first under point loads.

#Common mistakes

#Checklist before a mixed pallet leaves

• Heavy and strong on the bottom, fragile on top
• Layers flat, voids filled, no overhang
• Incompatible products separated
• Height and weight within the carrier and customer limits
• Wrapped and anchored to the pallet, top capped
• SSCC label on two adjacent sides, matching the ASN
• Case labels visible or recorded

A well-built mixed pallet is also cheaper to ship LTL, because a dense, stackable load gets a better class and fewer damage claims. See shipping pallets LTL.