Stockout

Stockouts have three recurring causes: demand that was underestimated, replenishment that reacted too slowly to a change in consumption, and inventory records that disagree with physical stock. The last one – phantom inventory – is the most persistent, because the replenishment system sees quantity that is not there and therefore orders nothing. In retail the damage goes beyond the missing margin: the shopper substitutes, defers the purchase, or buys the whole basket elsewhere, and repeated unavailability moves the category to a competitor.

• Stockout rate = SKU‑days out of stock ÷ total SKU‑days × 100 – the standard frequency measure.
• On‑shelf availability – measured at the shelf, not in the system; the gap against warehouse availability exposes phantom inventory.
• Lost sales = baseline demand during the stockout − actual sales, per item and location.

Zero stockouts is not the target. Above roughly 98 % availability the cost rises steeply, because every additional percentage point requires a disproportionate increase in safety stock. The decision is economic and taken per item: high‑margin, fast‑moving and traffic‑driving items justify a higher service level, while on slow movers the cost of the tied‑up stock exceeds the cost of an occasional stockout.

Stockout in practice

Cutting stockouts without inflating inventory means working on forecast accuracy and replenishment timing at the same time. Veritico STOCK sets safety stock per item and location from the target service level defined per ABC segment, and covers three sources of uncertainty separately: forecast error, day‑to‑day variability and supplier lead time. See demand forecasting and inventory optimization, replenishment and allocation management, and the Albert case study on availability in food retail.

Related terms

• Safety stock
• Replenishment
• On‑Shelf Availability (OSA)
• Service level
• Fill rate
• Phantom inventory