Stockout Cost Calculator
What running out actually costs you.
Cost of the stockout
$2,970
108 units of lost demand
The lifetime value component is usually larger than the lost sale, and it is the part that justifies safety stock.
How the Stockout Cost Calculator works
The obvious cost of a stockout is the margin on the sale you did not make. The larger cost is usually the customer who bought from someone else and did not come back — and once that is priced in, safety stock starts looking cheap.
Not financial advice. Marketplace fees change, and they vary by country, plan and seller status. Every rate here is an editable default, not a quoted price — check the platform's current fee schedule before you price a product against it. This is not tax or business advice.
Frequently asked questions
What does a stockout actually cost?
Lost margin on the immediate sale, plus the probability-weighted lifetime value of customers permanently lost, plus expediting costs if you rush a replacement, plus the ranking or visibility penalty some marketplaces apply to out-of-stock listings.
How do I estimate lost sales?
Take average daily sales for the product and multiply by the days out of stock. This understates it if the stockout occurred during a peak, and overstates it if buyers simply bought a substitute from you instead.
Do customers come back after a stockout?
Some do. Research on retail out-of-stocks consistently finds a meaningful share switch brand or retailer permanently, with the proportion rising for commodity items where substitutes are easy. Loyal customers for distinctive products are far more forgiving.
How does this justify safety stock?
Directly. Compare the annual carrying cost of a larger buffer against the expected annual cost of the stockouts it prevents. Where stockout cost is high — strong repeat purchase, easy substitutes — the buffer usually pays for itself several times over.