Free tools · Updated Oct 18, 2026
Stockout cost and reorder point calculator
When a product sells out, the sales you miss until it's back are gone unless shoppers wait for it. Enter one product's numbers to see what its stockouts cost per year, and the stock level at which you should reorder so it doesn't run out. Nothing is stored and there are no built-in averages.
Your result
$1,120 gross profit lost a year; reorder at 76 units
Showing results for the example numbers. Replace them with your own and press Calculate.
| Lost units per year | 64 |
| Lost revenue per year | $2,240 |
| Lost gross profit per year | $1,120 |
| Reorder point | 76 units |
| of which safety stock | 20 units |
This is arithmetic on the numbers above, not a forecast or a promise of savings.
How the math works
- Lost units per year = units per day × days out of stock × (1 − wait % ÷ 100)
- Lost revenue per year = lost units × selling price
- Lost gross profit per year = lost revenue × margin % ÷ 100
- Reorder point (units) = units per day × (lead time days + safety stock days), rounded up
- Safety stock (units) = units per day × safety stock days, rounded up
Automate the fix: Low-Stock Reorder Alert
Get an email + a ready supplier note the moment a variant hits your reorder point. Runs in free Shopify Flow, tested in a live Shopify store. $19 one-time.
Prefer to do it by hand first? Read Free Shopify Back-in-Stock Alert: Know the Moment a Sold-Out Item Returns.
FAQ
What is a reorder point?
It's the stock level that tells you to reorder. If you reorder when stock hits it, the new delivery should arrive before you run out, with your safety stock as a buffer.
How do I calculate units sold per day?
Take the units sold over a period when the product was in stock (for example the last 30 in-stock days) and divide by the number of days. Days when it was sold out would drag the average down.
Is lost revenue the same as lost profit?
No. If the product had been in stock you'd also have paid for the goods, so lost gross profit (revenue × margin) is the closer measure of what a stockout costs you.
Can Shopify alert me when stock hits my reorder point?
Shopify doesn't send reorder-point alerts by default, but Shopify Flow (free on Basic and up) can. Low-Stock Reorder Alert emails you and tags the product the moment a variant crosses your reorder point.