Stockout Cost Calculator

Free stockout cost calculator. Estimate the lost profit from a stockout based on daily demand, days out of stock, and profit margin per unit.

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Stockout Cost Calculator

Put a rough dollar figure on a stockout, so "we ran out for a few days" has a number attached to it. No signup required.

By Tibeau De Grauwe, FounderUpdated September 2026

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  • 25 products free
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  • 10-min setup

A stockout has a real, calculable cost beyond the immediate lost sale — but it's rarely put into a specific number, which makes it hard to weigh against the cost of holding more safety stock. This calculator gives a reasonable estimate: demand you couldn't fill, multiplied by what each unit would have earned.

Stockout Cost Calculator

units/day
days
$/unit
$

Estimated Stockout Cost

$400

≈ 50 units of unmet demand × $8/unit margin

How this estimate is calculated

Estimated Stockout Cost = (Average Daily Demand × Days Out of Stock × Profit Margin per Unit) + any one-time rush or expedite cost. It treats every unit of unmet demand during the stockout window as a fully lost sale, valued at your profit margin (not revenue) per unit.

Example: a product sells 10 units/day at $8 profit margin each, and you're out of stock for 5 days. Estimated cost = 10 × 5 × $8 = $400 in lost gross profit, before any rush-reorder fees.

This assumes lost sales are lost outright rather than recovered later as backorders — reasonable for most retail and e-commerce where a customer buys from a competitor instead, but less accurate for made-to-order or B2B relationships where customers may simply wait. Treat the result as a planning estimate for weighing against the cost of more safety stock, not a precise accounting number.

See also: the stockout glossary entry, how to reduce stockouts, the safety stock calculator.

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Frequently asked questions

How do you calculate the cost of a stockout?
A reasonable estimate is Average Daily Demand × Days Out of Stock × Profit Margin per Unit, plus any one-time rush or expedite cost incurred to resolve it. This values unmet demand at your profit margin rather than full revenue, since margin is what you actually lose.
Does this account for customers who come back later?
No, this calculator assumes lost sales are lost outright, which is the more common outcome in retail and e-commerce where a customer can simply buy from a competitor instead. If your business tolerates backorders (e.g., made-to-order or B2B), the real cost is lower than this estimate.
Why use profit margin instead of revenue in this calculation?
Revenue overstates what you actually lose, since it includes the cost of goods you didn't have to pay for the units you didn't sell. Profit margin per unit is a more accurate measure of the actual financial loss from a stockout.
How is stockout cost useful for deciding on safety stock?
Compare the estimated cost of a stockout against the carrying cost of holding enough extra safety stock to prevent it. If a stockout costs more than a year of holding the buffer stock that would have prevented it, increasing safety stock is usually the better trade.