When Should Retailers Use Case-Level Purchase Units? Practical Rules For Ordering And Inventory

Purchase Unit of Measure is the packaging level or unit in which inventory is purchased from a supplier.

Choosing the purchase unit—case, pack, each, or pallet—changes handling, storage costs, order frequency, and cash flow. For retailers deciding whether to order at the case level, this article lays out practical decision rules, cost and space trade-offs, and implementation guidance so you order in the most operationally efficient unit without sacrificing shelf availability.

When Case-Level Purchasing Is Appropriate

Ordering by case works well when the supplier’s standard pack reduces per-unit cost, when breakage or picking can be centralized, or when transportation economics favor consolidated loads. Case-level purchasing is common for non-perishable goods, high-volume SKUs, and when the retailer has the warehouse capacity to receive and break cases into sellable units.

When Case-Level Purchasing Is A Poor Fit

Avoid case-level if the SKU is slow-moving, has erratic demand, or has limited shelf life because overstock and markdowns rise. Small-format stores with limited backroom space or retailers relying on direct-to-store replenishment often prefer pack- or each-level purchasing to minimize manual breaking and inventory handling at the store.

Cost And Space Trade-Offs

• Unit cost: Cases usually offer a lower per-each price due to supplier economics and reduced packaging cost per unit.
• Storage footprint: Cases reduce inbound handling but require space for palletization and break-pack operations.
• Labor: Breaking cases into eaches adds labor steps either at the DC or store; factor labor cost into landed cost comparisons.

Operational Rules To Decide Case-Level Purchase

• Rule 1 - Demand Threshold: Only purchase by case when expected weekly demand exceeds the case quantity plus safety stock for the replenishment lead time.
• Rule 2 - Storage Capability: Verify the DC or store has space to store incoming cases and areas to break cases without disrupting flow.
• Rule 3 - Cost Parity: Calculate total landed cost including labor to break cases; choose the unit with the lower all-in per-each cost.
• Rule 4 - Freshness Constraints: For perishable goods, ensure case-level ordering won’t force product to sit past its sellable life before being put on shelf.

How To Configure Systems For Case-Level Purchasing

Set the purchase UoM on vendor records to case and capture the case-to-each conversion in the item master. Configure the WMS to accept ASN quantities at the purchase UoM and to generate putaway tasks that either put cases to reserve storage or route to break-pack stations. The ERP should invoice and post costs at the purchase UoM then prorate landed costs into inventory base units so margins are correct.

Example Calculation

If a case contains 24 eaches and costs $48 per case, per-each cost is $2. If breaking a case at the DC adds $0.10 per each in labor and $0.05 per each in packaging material, all-in per-each cost becomes $2.15. Compare that to buying a 6-pack at $14 (per-each = $2.33) or buying each at $2.50. If storage and transport capacity supports case ordering, case-level purchasing is the better economic choice.

Handling Mixed-Unit Shipments

Suppliers may ship mixed pallets containing both cases and full pallets. Ensure ASNs and PO lines clearly state UoM at the line level and that receiving staff scan the case GTINs. Where possible, require supplier pallet labels that show both case count and each count to speed receiving and reduce counting errors.

Tips For Rolling Out Case-Level Purchasing

• Pilot: Start with a subset of high-volume SKUs to validate cost math and receiving procedures.
• Vendor agreements: Negotiate case quantities and require case GTINs on labels and ASNs.
• Cross-functional alignment: Involve merchandising, procurement, receiving, and store operations in the decision to ensure all teams understand conversion and allocation rules.

In short, the Purchase Unit of Measure should be chosen based on demand, storage and labor capacity, and total landed-cost comparisons. Case-level purchasing often reduces per-unit cost and simplifies shipping, but only when operational capacity and product characteristics support breaking and allocating case contents without creating excess risk or expense.