What is Stockout Rate?

Why It Matters

Stockout rate turns an invisible problem, empty shelves or sold-out listings, into a trackable number a merchandising or supply chain team can act on. Every SKU that's out of stock is a SKU that generates zero revenue no matter how strong its demand is, so a rising stockout rate during a demand spike represents real, quantifiable lost sales rather than just a logistics inconvenience. It also affects customer trust, since shoppers who repeatedly find a favorite item unavailable often stop checking back at all. Tracking it alongside reorder timing and demand forecasts helps teams catch supply gaps before they compound into a bigger revenue hit. Left unmonitored, stockouts on best-selling SKUs can quietly erode a period's numbers while every other metric looks fine.

Example

A retailer carries 500 active SKUs, and on average 25 of them are out of stock at any given time during a month. Stockout rate is 25 divided by 500, times 100, which equals 5%. If stockout rate rises to 12% during a demand spike without a corresponding increase in reorder volume, that gap represents direct lost revenue on the affected SKUs, which is why stockout rate is tracked alongside backorder rate and days sales of inventory to catch supply gaps before they compound during high-demand periods.

Frequently Asked Questions

• Does stockout rate count partial unavailability, like one size or color?

  Most retailers count a SKU as stocked out only when that specific SKU, such as one size or color variant, has zero available units, not when the broader product is merely low on stock elsewhere.

• How is stockout rate different from days sales of inventory?

  Days sales of inventory measures how long current stock will last at the current sales pace, while stockout rate measures how often that stock actually ran out, the outcome DSI is trying to help you avoid.

• What's considered a healthy stockout rate?

  Many retailers aim to keep stockout rate under 5 to 8% for core, high-velocity SKUs, though tolerance is higher for long-tail or seasonal items that aren't expected to always be in stock.

• How often is stockout rate typically monitored?

  Fast-moving retail and ecommerce operations often check it daily or in near real time, since a stockout on a top-selling SKU can lose meaningful revenue within hours during peak demand.

• What usually causes stockout rate to spike?

  The most common causes are demand forecasts that underestimate a sales spike, supplier or shipping delays, and reorder points set too low relative to actual sell-through speed.