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How to prevent stockouts on Shopify
Most stockout advice amounts to hold more stock, which is expensive advice. These are the changes that reduce stockouts without simply tying up more cash, in roughly the order they pay off.
Last reviewed 16 August 2026
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1. Make the underlying data trustworthy
Every other step reads from your stock numbers. If those are wrong, good thresholds and good alerts produce confident nonsense.
- Count regularly. Cycle counting a slice of the catalogue each week beats an annual full count that is stale a month later.
- Fix shrinkage as a process problem. Persistent discrepancy usually means receiving or picking is not being recorded, not that stock is disappearing.
- Check the continue selling setting. Variants set to keep selling past zero go negative, which distorts every calculation downstream.
2. Set thresholds from lead time
The single highest leverage change most stores can make. A round number applied catalogue wide alerts too late on fast movers and constantly on slow ones.
Average units per day, multiplied by honest days to restock, plus a buffer. Worked examples in how to set a low stock threshold.
3. Measure your real lead times
Almost everyone underestimates this and the error propagates into every threshold.
For your top products, look at the last three orders and record the days from deciding to order to the stock being sellable. Include approval, production, transit, customs and receiving. Use the longest of the three rather than the average, because the threshold exists to survive the bad case.
4. Make the warning arrive on its own
A threshold nobody checks prevents nothing. This is where most stockouts actually come from: the data was right, the threshold was reasonable and nobody opened the screen during the week that mattered.
Free options exist. Shopify Flow is free on paid plans and covers the basic case. The requirement is only that something arrives without being asked for.
5. Send it to more than one person
Alerting a single person means the system has a holiday shaped hole in it. Peak season and annual leave overlap more often than anyone plans for.
At minimum: whoever raises the orders and one person who notices when they have not. More on this in making inventory alerts get acted on.
6. Check each location separately
If you hold stock in more than one place, total stock is not a safety signal. Plenty overall with nothing where the demand is still means you are out.
Evaluate per location against a threshold reflecting what that site sells and how quickly it can be replenished. See alerts across every location.
7. Prepare before peaks, not during
Peaks are where the two risks compound: demand rises exactly when supplier lead times stretch.
- Raise thresholds ahead of the peak to reflect the higher sales rate and the longer lead time.
- Order earlier than feels necessary. The reorder point you calculated on normal conditions is too low for a peak.
- Review daily during the peak rather than weekly.
- Reset afterwards, so peak thresholds do not leave you overstocked all year.
What not to bother with first
Demand forecasting software is usually the wrong first purchase. Forecasting improves a number you are probably not acting on yet. If your thresholds are round numbers and nobody is alerted, a better forecast changes nothing about the outcome.
Get the basics running, spend a season learning where your alerts were wrong, then buy forecasting if the remaining gap is genuinely predictive rather than operational.
Start with the step that pays fastest
Of the seven, making the warning arrive on its own is the cheapest and the fastest to set up. Stockwell watches every SKU at every location and emails your team before stock hits zero.
Get Stockwell on the Shopify App Store Free plan covers 50 SKUs with a daily summary. Paid plans add instant alerts and more recipients. No card needed to start.Common questions
What is the most common cause of stockouts?
Not bad forecasting. In most stores it is that stock levels were accurate and reasonable thresholds existed, but nobody looked during the week it mattered. Duration of an undetected stockout is what multiplies the cost.
How do I prevent stockouts without holding more inventory?
Set thresholds from real lead times rather than round numbers, make the warning arrive without being asked for, send it to more than one person and evaluate each location separately. None of that requires holding more stock.
Should I buy demand forecasting software?
Not first. Forecasting improves a number you may not be acting on yet. Fix thresholds and alerting, run a season, then decide whether the remaining gap is predictive or operational.