Ecommerce
A stockout costs more than the margin on the sale you missed, because some of those customers do not come back.
The lost sales
Units of demand you could not fulfil.
Price per unit, in your local currency.
Cost per unit, in your local currency.
The customers you do not get back
Multiplier for lost future business (1 = direct margin only).
Estimated Stockout Cost
3,000.00
Direct lost margin scaled by the loyalty loss factor.
Formula verified 13 September 2026
Direct Lost Margin
2,000.00
Lost units multiplied by margin per unit.
Lost Units
100
Units of unfulfilled demand entered.
Estimate only — platform fees and costs vary; verify current rates. Read the full disclaimer ↓
Each step from margin per unit to the final estimate, computed from your inputs. The direct loss is pure missed profit; the loyalty factor scales it up for customers who may not return after finding the shelf empty.
| Step | How it is found | Amount (local currency) |
|---|---|---|
| Margin per unit | 40 price − 20 cost | 20 |
| Direct lost margin | 100 lost units × margin | 2000 |
| Loyalty uplift | × 1.5 repeat-loss factor | 1000 |
| Estimated stockout cost ◀ | Direct loss × loyalty factor | 3000 |
Estimates only — not financial, tax, or professional advice.
100% private — every number you enter is calculated in your browser and never sent to our servers.
What it calculates: Estimated Stockout Cost, Direct Lost Margin, Lost Units.
Updated 5 June 2026 · Transparent assumptions
A missed sale does not cost the full selling price, because you also did not incur the cost of the goods. The immediate loss is the contribution margin — price less unit cost — on every unit you could not supply.
Reporting stockouts as lost revenue overstates the damage substantially on low-margin lines, and it is the figure that makes people over-invest in buffer stock for products that barely contribute.
A customer who finds an empty shelf may wait, may buy a substitute, or may buy from a competitor and stay there. The repeat loss factor prices that last group — the future margin from customers the stockout permanently cost you.
For a business with genuine repeat purchase, this term usually dominates the immediate margin loss. It is also the term hardest to measure, which is why it is an input you set rather than a figure assumed for you.
Every other cost in a business generates a transaction. A stockout generates nothing — no order, no line item, no entry anywhere — which is why it is chronically under-managed relative to costs of similar size.
The proxies are out-of-stock days weighted by a normal sales rate, and for online catalogues, sessions that landed on an unavailable product. Neither is exact, and both are better than treating the cost as zero.
The figure here is what justifies safety stock. Set it against the carrying cost of the buffer that would have prevented the stockout, and the right level of protection follows from the comparison.
High-margin fast-moving lines with loyal customers justify deep buffers. Low-margin slow lines rarely do, and treating every product the same is how a catalogue ends up simultaneously overstocked and out of stock.
Figures on this page are checked against primary, authoritative sources. Links open in a new tab.
Business disclaimer
Results are estimates for planning and analysis based on the figures you enter. They are not accounting, tax, or financial advice — verify with your own records and a qualified professional before making decisions.
How we calculate · Found an error? email us
Published 13 September 2026