How Retailers Keep Popular Products on Shelves

1. Don't rely on sales figures for products that sell out too quickly. In my uncle's convenience store, for example, we used to run out of bottled water by 2 pm on summer Saturdays. The till would then tell us that we had sold 40 cases of water. In reality, we had sold 40 cases of water and then denied service to everyone else who wanted to buy water after that. The demand for products was limited by the space on the shelves, not by the demand from customers. So the key figure for me to understand the impact of stock is not the number of stock items sold but the time of day when stock is completely sold out. A product that is completely sold out at 2 pm requires a different solution than a product that is completely sold out at 7 pm. And I look at solutions in terms of hours of empty shelves they remove, not in terms of quantity. And often the bottleneck is not the stock held at the front of the shop but the stock held in the back room just 10 meters away from the shop.

2. Set a par level for every shelf and check it on a set time every day. I had the stockers put up a small number of items on tape under every essential item (like milk and water) and then every 11 hours, 3 hours, 7 hours, etc., someone would go through the aisles to re-stock from the back room to try to hit the number on the tape. It took about 10 minutes to go through the aisles and all of a sudden empty-shelf complaints would disappear. And when we did re-order, I never had to wonder whether to order extra; most items would run out right on the number I had set for the re-stock. And if the 7 p.m. re-stock needed something that wasn't in the back room, that item would get put on the next day's order for re-stock. So most of what I would have called supply problems were really just problems with refilling stock.

I first work out why the product sold out. Was demand underestimated, was the supplier late, or was the reorder simply too small? The fix is different for each cause.

The replenishment practice that helped most is a clear reorder point for every essential item. I set it using the supplier's lead time plus a safety buffer, and we reorder the moment stock reaches that number rather than waiting until the shelves look bare. We keep a short list of 10 to 20 essentials that get this treatment and let the long-tail items run on leaner stock. We review that list every month.

Cash is limited, so I put the buffer where a stockout would lose loyal customers, not spread it equally across every item.

Keeping availability starts with measuring what actually sells, by channel, then changing the reorder logic rather than the product. We focus on sell-through and supplier lead time to decide whether to raise reorder points, split larger orders into more frequent smaller replenishments, or limit promotional exposure that accelerates stockouts.

One practice that helped us: automated reorder triggers tied to dynamic reorder points that update weekly from recent sell-through and current supplier lead times. When a best-seller repeatedly ran out, we raised its reorder point and moved to twice-weekly small replenishments with the supplier, which reduced repeat stockouts without inflating overall inventory.

The most effective change we made to replenishment was moving from a fixed schedule to an exception-based routine. We created a daily list that flags items when sales rise faster than available stock can support. To separate real demand spikes from temporary changes, we compare recent sales with past seasonal patterns, current traffic, and incoming inventory. This helps us identify which items need attention before stock runs low.

The process gives our buyers a short, ranked list of decisions instead of a large report to review. We focus on items with a high risk of running out and a realistic chance of recovery. We review false alarms regularly and adjust our limits. This helps us treat forecasts as changing signals rather than fixed plans.

I start by finding the few items that run out first, because it's almost always the same short list of cheap essentials. In a vacation rental that means toilet paper and paper towels. A guest who hits an empty roll remembers it for the whole review.

The change that helps most is tying the refill to a visit that already happens. On every turnover, the cleaner tops up the paper goods before leaving, including trash bags. The host's cabinet stock gets used first. The cleaner's kit carries a backup supply, so the shelf is full when the door locks even if the cabinet was bare. Nobody has to remember anything, because the refill rides along with the clean.

The person standing at the shelf sees the gap before any report does. So I give that person the authority and the supplies to fix it on the spot. Reorder dashboards and forecasts come second, once the basic top-up works every time.

Soap, shampoo and coffee stay with the host. Brands and preferences vary by property, and a guess at the wrong one creates a new problem.

Start with the top sellers, not the whole catalog. When popular items keep selling out, it is usually because their reorder points were set once and never revisited as demand grew. Recalculate them for your fastest movers using recent sales and the lead time your supplier actually delivers, not the one it quotes.

Then look at when you order, not just how much. Most stockouts are decided weeks earlier, when the order should have gone out. Work backward from the day the shelf runs empty, subtracting receiving, transit and production time. That gives you the real order deadline.

The practice that has helped most: review your best sellers weekly on a fixed day, and log promised versus actual ship dates for each supplier. After three or four orders you know which suppliers need more buffer, and essential items stop running out for reasons you could have seen coming.

Andrew Gladue, founder of Skuvelo (skuvelo.com), APICS CPIM and CSCP If you use this, please name Skuvelo and link to skuvelo.com. Happy to answer follow-ups by phone at (321) 758-8356.