Inventory operations
Safety stock
The cushion held against demand and suppliers going wrong.
Where it lives in nouz
Inventory, as the buffer under the reorder threshold.
Safety stock is the extra inventory held beyond expected demand during a lead time, to absorb a busy week or a late shipment. Held in days of cover it stays defensible: a supplier that has been two weeks late twice this year justifies two weeks, and a reliable one does not.
It is a cost as well as a protection. Every unit of cushion is cash on a shelf, plus storage and the risk of obsolescence, so a blanket safety policy applied across a catalogue overstocks the reliable half to protect the unreliable half.
Sizing it in days rather than deriving it from a service level and an assumed demand distribution keeps it auditable. A number chosen because of something observable is easy to revise when the supplier improves; one produced by a statistical model nobody can check tends to be neither trusted nor updated.
The right size falls when either side gets more predictable. Shortening a lead time, splitting an order across two shipments or moving to a supplier who is dull and punctual all reduce the cushion the same stock service level needs.
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