Summary
Case picking is picking full, sealed cases of one SKU to fill an order. It sits between piece picking (single units) and pallet picking (whole pallets), and it is the standard method for store replenishment, wholesale and B2B distribution. Picked cases usually go straight onto a pallet, so case picking is also pallet building, and the order of the picks decides whether the pallet arrives standing.
A store orders 40 lines of drinks, cleaning products and snacks. In a case picking operation, that order is a walk with a pallet jack through the pick faces, and the pallet is built on the forks as the picker goes. The walk costs time, and a badly built pallet costs damaged goods, a restack at the dock or a refused delivery.
Most of that walking and damage traces back to how cases are slotted and sequenced. Slotting and pick sequence can both be changed on top of your current WMS, without buying robots.
What is case picking?
Case picking is an order picking method in which the picker takes full cases or cartons from a pick location and places them on a pallet, cart or conveyor. A case holds a fixed number of units of one SKU as the supplier packed it, such as 24 cans, 6 bottles or 12 bags, and the picker never opens it.
A case is one level in the unit of measure hierarchy: each (the single saleable unit), inner pack, case, layer and pallet. The item master holds how many of each level fit into the next one up, and when that data is wrong, a case pick turns into a counting job.
Full case, split case and layer picking
- Full case picking: whole sealed cases. Most people just call it case picking.
- Split case picking, also called broken case picking: the case is opened and loose units are picked from it. In practice this is piece picking from a case-sized pick face.
- Layer picking: a full layer of cases taken off a pallet in one move, usually with a layer clamp on a lift truck.
What does a case picker do?
A case picker follows a route of pick locations, takes the requested number of cases from each, confirms them with a scanner or voice system, and stacks them on the pallet or roll cage. On a double pallet jack or a low-level order picker, one person often builds two pallets in a single tour.
At 100 cases an hour and an average of 10 kg a case, a picker lifts a tonne of product every hour. That is why case weight, pick height and the order of the picks matter far more here than in each picking.
One order, three units of measure
The picking method is set per order line, so one customer order can need several. Take a wholesale order for 2,000 cans of a soft drink that comes 24 to a case and 80 cases to a pallet.
- One full pallet of 80 cases, or 1,920 cans, is a pallet pick, moved from reserve by a lift truck.
- Three cases, or 72 cans, are case picks from the pick face.
- The last 8 cans are a split case pick.
One order line touches three pick processes, and the WMS needs all three conversion factors to split it. Many sites round to full cases by customer agreement instead, which keeps loose-unit work out of the case pick aisles.
Case picking vs piece picking vs pallet picking
The three methods differ in the unit the picker handles: single units in piece picking, sealed cases in case picking and whole pallets in pallet picking. That one difference changes the pick face, the equipment, the cost and what goes wrong.
| Piece (each) picking | Case picking | Pallet picking | |
|---|---|---|---|
| Unit handled | Single saleable units | Full sealed cases of one SKU | A complete pallet, cases untouched |
| Typical orders | E-commerce, small B2B orders, samples | Store replenishment, wholesale, B2B distribution | Bulk replenishment, large wholesale, cross-dock |
| Pick face | Shelving, carton flow, totes | Floor-level pallet positions, pallet flow, carton flow | Reserve racking or floor stock |
| Equipment | Trolley or cart with totes or boxes | Pallet jack, low-level order picker, roll cage | Reach truck or counterbalance truck |
| Main cost | Many picks and travel per line | Travel, lifting and pallet build time | Truck travel per pallet |
| Main risk | Wrong item or quantity | Crushed cases, unstable pallets, strain injuries | Wrong pallet, handling damage |
View this comparison on desktop for the full data table.
When each method fits
Case picking fits when customers order in full-case multiples often enough that cases can leave sealed. Store replenishment is the textbook example: a supermarket orders 4 cases of pasta and 2 of olive oil, never 7 single jars.
Piece picking fits when order lines are smaller than a case, which describes most of e-commerce. Those operations run on totes, trolleys and a pack station, a different flow that we cover in our article on pick and pack operations.
Pallet picking fits when one SKU fills a full pallet for one customer. It is the cheapest unit to move and the least common one in a mixed-order operation.
Most warehouses run all three
A distribution center that serves stores rarely gets to choose one method. The order profile decides the mix, line by line, so start from the share of your order lines that are full pallets, full cases and eaches.
Take a month of order lines and divide each quantity by the case quantity and the pallet quantity from the item master. If most lines land on whole cases, case picking is your main flow. If the share of eaches keeps growing, a separate split case zone usually works better than opening cases in the case pick aisles, because loose units and sealed cases need different pick faces and different equipment.
How is a case picking operation organized?
Four decisions shape a case picking system: where cases are presented, which SKU sits in which location, the order in which cases are picked, and how orders are grouped into tours. The first two are set in the layout and the slot plan, the last two every time a pick list is released.
1. Pick faces and storage
Most case pick areas present cases at floor level, in pallet positions on the bottom beam of the racking, with reserve stock above. Fast movers often sit in pallet flow lanes, so a full pallet feeds the pick face from behind, while slow movers go into carton flow or shelving.
The working rule is that every case should be reachable between knee and shoulder height. Picks from the top of a tall pallet or the back of a deep location are where the seconds and the back strain go.
2. Slotting by velocity, weight and crush strength
Standard warehouse slotting puts fast movers close to the start of the route. In case picking, weight and crush strength have to count as well, because the slot decides where in the walk a case comes up, and so where on the pallet it lands.
Heavy, rigid cases such as bottled water, canned goods and detergent belong early in the walking sequence. Light or crushable cases belong near the end, for example snacks, paper towels and eggs. A fast-moving case of water slotted at the far end of the last aisle forces a choice between walking back and putting it on top of the snacks.
3. Pick sequence for pallet stability
Whatever the picker takes first goes on the bottom of the pallet, so a route sorted only by location number stacks the cases in whatever order the aisles happen to run.
A stable mixed pallet needs a different logic: heavy and square cases first, a level surface before each new layer, crushable and irregular cases last. Many sites teach pickers that rule and leave them to rearrange the pallet at the end of the aisle, which adds build time nobody planned for.
4. Batching and multi-pallet picking
Case pickers often build two pallets at once on a double pallet jack, or pick several store orders in one tour. The limits on a case picking batch are physical: pallet footprint, pallet height, total weight and what the truck can carry, on top of the number of orders.
Batch, cluster, zone and wave picking all apply to cases, and they are compared in our full guide to warehouse picking strategies. In case picking, a batch only works if every pallet in it can still be built in a stable order.
What are the typical problems in case picking?
Most case picking problems show up at the end of the process, at the dock or at the customer, while the cause sits earlier in the slot plan or the pick list.
| Symptom | Likely cause | Where to look first |
|---|---|---|
| Crushed or dented cases at the customer | Light cases picked before heavy ones | Pick sequence and slotting by weight |
| Pickers restack pallets at the end of the aisle | Pick list sorted by location, not by stacking order | Sequence rules in the pick list |
| Leaning or overhanging pallets at the dock | Mixed case sizes with no build plan | Pallet build rules and batch limits |
| Long walks for a few lines per tour | Fast movers spread across the building | Slot plan by velocity |
| Picks per hour falls while headcount rises | Too many pickers in a few busy aisles | Slotting and wave release |
| Split case lines slow the case pick aisles | Loose units picked from case locations | A separate split case zone, or rounding to full cases |
| Back and shoulder complaints | Heavy cases picked from high or deep positions | Pick face height and slotting by weight |
View this comparison on desktop for the full data table.
Travel is the biggest single block of picking time: an open-access 2023 study in Axioms puts it at 55%↗, and case picking adds the pallet jack, the turning space at aisle ends and the trips back for a second pallet.
The physical load shows up in injury data. A 2024 report by the U.S. Government Accountability Office found that transportation and warehousing had the highest serious injury and illness rate of all 19 sectors in 2022, about 3.8 cases per 100 workers, with overexertion, such as moving unsafely while lifting or bending, the most common cause of injury↗. In a case pick area, that points straight at case weight and pick height.
To find out which rows apply to you, compare the WMS pick sequence for a few dozen tours with the way the pallets left the aisle. If pickers routinely change the order of the picks, they are working around the sequence logic, and that logic is what needs fixing.
Why is case picking hard to optimize?
The shortest route and the best pallet usually want a different order. The route wants cases in aisle order, the pallet wants them by weight and strength, and every case picking operation lands somewhere between the two.
A WMS typically sorts the pick list by location sequence, the order in which aisles and bays are numbered, which gives a short walk and an arbitrary stack. If the heaviest SKU on the list sits in the last aisle, it either goes on top or the picker walks back for it.
What a bad build costs
Crushed cases are the damage you can see. A case that hangs over the pallet edge also loses strength fast: in a 2024 simulation study in Applied Sciences, one box size lost 12% of its compression strength at just 1% overhang, and the loss was roughly twice as large when a box overhung on two sides↗. Cases end up overhanging or bridging gaps on pallets built in the wrong order.
Researchers see the same difficulty from the software side: a 2024 review of mixed palletizing methods in Sustainability notes that handling weight limits, stacking stability and item compatibility "is not straightforward"↗, even for algorithms and robots. A picker solving it in their head on every tour, all shift long, has a harder job than the pick list suggests.
Why the floor cannot fix it alone
Fixing the order on the floor costs time, and every restack is pallet build time that the labor plan does not count. Experienced pickers develop their own rules, which work well until a new SKU arrives, the slot plan changes or a new picker starts during peak. Our article on mixed palletizing in pick and pack operations goes deeper into the route versus stability trade-off.
Mixed case palletization: building the pallet from picked cases
When the picked cases of many SKUs go onto one pallet for one store or customer, the result is a mixed case pallet, also called a mixed SKU pallet. It is daily work in food and beverage distribution, where a single store pallet can carry cans, glass and plastic bottles, drink cartons and kegs, because a shop orders many products and few of them in full-pallet quantities. Weight order is only one of the rules a mixed pallet has to meet. The cases also have to fit the pallet footprint without overhang and stay under the height and weight limit of the pallet and the truck, and some products may not share a pallet at all, such as hazardous goods and food. If an order does not fit on one pallet, someone has to decide which cases go on the second.
Sites build mixed pallets in four ways: by hand on the picker's own judgment, with software guidance, with robots that carry the pallet between pick locations, and in fully automated palletizing cells. With software guidance, palletization software calculates a stable mixed pallet before picking starts, and the picker follows 2D or 3D stacking instructions on a handheld or tablet. When the pick list is sequenced to match that plan, the cases come up in the order they go onto the pallet, and new or temporary pickers can follow it from their first shift. Our article on the four types of mixed palletization compares them and covers when it makes sense to automate.
How to improve case picking on top of your WMS
None of these fixes needs new racking or robots. They change the information a picker gets, and they work best in this order because each step uses the one before it.
- Clean the case data. Check case dimensions, weights and units per case in the item master against the physical case, because every later step depends on them.
- Give every SKU a stacking class. Three classes are enough to start: heavy and rigid, standard, crushable or irregular.
- Re-slot by velocity and by stacking class. Move heavy fast movers toward the start of the route and crushable ones toward the end, ten or twenty moves at a time rather than one big re-slot.
- Sequence the pick list for the pallet. Heavy and rigid first, crushable last, with the shortest walk inside those rules.
- Batch with physical limits. Cap tours on pallet footprint, height and weight, and balance the weight between the two pallets on a double jack.
- Test before moving anything. Run the new slot plan and rules on a month of real orders and compare walking distance and pallet builds with today.
Steps 1 to 3 are a slotting job that a spreadsheet can carry for a small range. Steps 4 and 5 happen on every pick list, hundreds of times a day, and that is where a WMS rule set runs out.
What an optimization layer adds
An optimization layer sits between the WMS and the picker. The WMS keeps the orders, the stock and the confirmations, while the layer decides which orders share a tour and in which order the cases are picked, and sends that plan back to the WMS for execution.
Pulse, Optioryx's warehouse optimization platform, does this for case picking with constraints that a location sort cannot hold. Order clustering closes a batch at a maximum weight, pallet surface or weight difference, as well as at a number of orders or picks. For pick-to-pallet flows the route can follow heavy-first sequence rules. Pulse's packing optimization, which runs as its own workflow on the same platform today, produces pallet build plans with step-by-step stacking guidance for the operator.
Slotting runs on the same platform, with stackability as one of the slotting objectives, so heavy and rigid SKUs are placed where the pick sequence needs them. Across customer deployments, clustering, routing and slotting together cut walking distance by up to 50%, and pick-and-stack operations run with around 10% fewer pickers.
You can start in the web app with order history and a layout, before any WMS integration, and see the routes and walking distance next to today's numbers. The integration puts the result on the floor, so prove it on your data first and connect afterwards. A digital twin of the pick area lets you test a slot change or a new aisle direction the same way, before anyone moves a pallet.
Questions?
Case picking means filling an order with full, sealed cases of one product, a level between single units and whole pallets. The case leaves the warehouse as the supplier packed it, usually stacked on a pallet or roll cage. It is the standard method for store replenishment, wholesale and B2B distribution.
A case picker follows a pick list through the case pick area, takes the requested number of cases from each location, confirms them with a scanner or voice system, and stacks them on a pallet or cart. The picker usually builds the pallet during the route, so the order of the picks decides how stable the load is. The work means a lot of repeated lifting, which is why case weight and pick height matter.
Case picking takes individual sealed cases from a pick face and builds them into an order, often a mixed pallet of many SKUs. Pallet picking moves a complete pallet of one SKU from storage to the dock without handling the cases. A pallet built from separately picked cases counts as case picking plus pallet building.
Split case picking, also called broken case picking, means opening a case and picking loose units from it because the order line is smaller than a full case. It is piece picking from a case-sized location. Many distribution centers keep it in a separate zone so that loose-unit work does not slow down the full case aisles.
Pulse runs on top of your existing WMS and decides which orders share a tour and in which order the cases are picked. Batches respect weight and pallet surface limits, the pick sequence can follow heavy-first stacking rules, and slotting can treat stackability as an objective. Across customer deployments, clustering, routing and slotting together cut walking distance by up to 50%.