Stock risk: how to avoid running out of your best-selling products

There’s one mistake that costs every e-commerce store dearly and often goes unnoticed until it’s too late: running out of stock on a product that sells well. It’s called stock risk, and it’s one of the most underrated risks in managing a PrestaShop store.

Why out of stock is a double blow

When a best seller runs out, you don’t just lose those days’ sales. You lose on two fronts:

1. Immediate missed sales: every visit to the product page that doesn’t turn into an order is lost revenue.
2. Ranking: if you were advertising that product, you keep paying for clicks that don’t convert. And if the page ranked well on Google, prolonged unavailability can drop its ranking.

There’s also the less visible damage: the customer who can’t find the product goes to a competitor — and may stay there.

What stock risk is

Stock risk is the estimated chance of a product running out, calculated by combining two pieces of information:

• the current inventory (how many units you have);
• the sales velocity (how many you sell per day/week).

From this you get the metric that really matters: the days remaining before running out. A product with 40 units in stock looks safe, but if you sell 10 a day you only have 4 days of runway.

Why “stock level” alone isn’t enough

Many merchants set an alert when stock drops below a fixed threshold (e.g. 10 units). The problem is that a fixed threshold doesn’t account for sales velocity.

Ten units of a product that sells 1 a week is 70 days of runway: no urgency. Ten units of a product that sells 15 a day is already past the critical threshold. The right threshold isn’t an absolute number, it’s a time horizon.

How to monitor it proactively

1. Focus on high-volume products. Stock risk matters most on best sellers: they cause the most damage when missing.
2. Think in days, not units. Set alerts on the remaining days of coverage.
3. Anticipate spikes. Sales, holidays and campaigns increase sales velocity: recalculate stock risk in those periods.
4. Automate the alert. You can’t check the warehouse every day: you need a system that warns you when a product enters the risk zone.

Stock risk in NothingSell

NothingSell includes a Stock Risk widget that automatically cross-references inventory and sales velocity of your PrestaShop products, estimating the days remaining before they run out — with alerts when a product enters the critical zone.

And with the PrestaShop MCP you can simply ask the AI: “Which products are at risk of running out in the next 7 days?”

In short

Stock risk is a silent threat that hits exactly where it hurts most: on the products that sell. Monitor it in days of runway, not units, and automate the alerts.

👉 Discover the Stock Risk widget among the NothingSell features or connect your PrestaShop for free.