Inventory glossary

What is Stockout cost?

Stockout cost is the financial loss a store takes when a product is out of stock and a customer cannot buy it.

Stockout cost helps you decide how much safety stock is worth holding. If a SKU has a high stockout cost, it makes sense to keep extra buffer even if that ties up some cash, because the lost sale and lost customer are more expensive than the holding cost.

Use it to prioritize which SKUs need closer attention. A $5 keychain running out for a week barely matters. A best selling candle running out during the holiday season can cost real money and send customers to a competitor.

Formula

Stockout cost = lost units x contribution margin per unit (plus any estimated cost of lost future sales)

Example

A candle store sells a scent for $20 with a $12 margin. It goes out of stock for two weeks and the store estimates it would have sold 15 units in that time. The direct stockout cost is 15 x $12, which is $180, not counting any customers who never come back.

Common mistakes

  • Only counting the lost sale and ignoring customers who leave for good.
  • Not weighing stockout cost against the carrying cost of holding more safety stock.
  • Treating every SKU the same when slow movers rarely matter as much as bestsellers.

Stockout cost and SteadyShelf

SteadyShelf forecasts demand per variant and flags an order-by date per SKU so you can reorder before stock runs out and avoid this cost.

SteadyShelf is launching on the Shopify App Store. Join early access to get the install link first.

Related terms

Stockout · Safety stock · Reorder point · Lost sales · Service level

Full inventory glossary

FAQ

Is a stockout always a lost sale?

Yes, usually. A customer who hits a sold out page may buy from a competitor instead. Some will wait, but many stores lose that sale permanently, especially for impulse or seasonal items.

Can you calculate stockout cost exactly?

Only roughly. You can estimate lost margin and refund costs, but goodwill loss and future customer churn are hard to measure exactly. Most stores use it as a planning signal, not an exact accounting figure.

Let SteadyShelf do this math for every SKU

Order-by dates per supplier, seasonal forecasts and draft POs for your Shopify store. $29/month after a 30-day free trial.

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