What is Stockout Rate?

Stockout rate measures how often your products are unavailable for purchase due to zero inventory. It can be expressed as a percentage of SKUs out of stock at any given time, the percentage of time a specific SKU is out of stock over a period, or the percentage of customer demand that could not be fulfilled due to stockouts. Regardless of the specific calculation, stockout rate quantifies lost sales opportunities.

Why It Matters

Every stockout is a missed sale—and often a customer lost to a competitor. Research shows that 21–43% of customers will buy from a competitor when their preferred product is out of stock, and many will not return. Beyond immediate lost revenue, stockouts damage your search ranking on marketplaces (lower sales velocity = lower ranking), reduce your advertising ROI (paying for traffic that cannot convert), and erode customer trust over time.

How It Works

• SKU-Level Stockout Rate: Percentage of active SKUs currently at zero inventory. If 50 of your 500 SKUs are out of stock, your stockout rate is 10%.
• Time-Based Stockout Rate: Percentage of days (or hours) a specific SKU was out of stock over a period. If a SKU was out of stock for 6 out of 30 days, its stockout rate is 20%.
• Demand-Weighted Stockout Rate: Weighted by sales velocity so that stockouts on best-sellers have more impact than stockouts on slow movers. This is the most actionable measure.
• Lost Sales Estimation: Estimate revenue lost to stockouts by multiplying the stockout period by the average sales rate during comparable in-stock periods.

How Nventory Helps

Nventory tracks stockout events in real time across all channels and products, calculating stockout rates at SKU, category, and channel levels. The system estimates lost revenue from stockouts, alerts you before products reach zero inventory (based on velocity and lead time), and provides trend analysis showing whether your stockout problem is improving or worsening.