Why the receiving unit needs a definition
A supplier may describe a shipment in cartons while the sales channel orders individual pieces. If the two systems use different pack quantities, a correct carton count can still produce an incorrect available-unit balance. Give each SKU an explicit receiving unit, sale unit and conversion rule before the first arrival.
Work through one SKU
Consider a planning example: one carton contains 12 individual units, and 20 cartons arrive. Before damage, reservation or other adjustments, the physical quantity is 240 units. If five units are dispatched, 235 remain. The example is arithmetic, not a claim about an actual customer project. Agree how the record represents the opened carton and whether it can still fulfil a full-carton order.
Record pack changes as a new instruction
A pack quantity can change between production batches. Provide effective dates or batch references for the new packaging, and distinguish it from existing stock. A promotional set containing two different products needs component quantities and a way to identify the finished set. Do not change a product’s historical conversion rule to make a new receipt fit.
Separate quantity from availability
Define how damaged, reserved, returned and held stock affect the available balance. A physical count answers how many units are present; a saleable-stock balance answers which units can be allocated. For customs-supervised inventory, the proposed unit handling and movement must also support the applicable records and procedure.
Prepare a short test file
Send several sample SKUs with barcodes, units per carton, mixed-pack instructions, batch fields and expected order units. Include a full-carton receipt, a partial-unit dispatch, an opened carton and a discrepancy. Ask the parties handling the systems to reconcile the example before setting a launch date.