Does Your Bestseller Run Out Right When It Sells the Most? The Reorder Point That Stops Lost Sales (Without Freezing Cash in Your Store)

Does Your Bestseller Run Out Right When It Sells the Most? The Reorder Point That Stops Lost Sales (Without Freezing Cash in Your Store)

Two scenes play out every week in thousands of small businesses. The first happens in front of the shelf: a customer comes in for a product you sell every day, finds the space empty, asks if there is more in the back and, when told there is not, walks out the door determined to buy it from a competitor. The second happens quietly, at the back of the warehouse: boxes of a product that barely sells have been sleeping on the racks for months, with the company's money locked inside them, gathering dust and, in some cases, getting closer to their expiration date.

The first scene is a lost sale. The second is idle capital. Both drain money from the business every month, and both come from the same cause: not knowing precisely when to order merchandise or how much to order. The good news is that this has a solution and it does not require guessing: it is called minimum stock and reorder point, two numbers calculated per product with simple data that any small business already has. In this article we show you how to do it, with the formulas, a complete worked example in a table and the steps to apply it this very week.

Running out of stock costs more than the lost sale

When a shelf is empty, you do not only lose the selling price of that unit. You lose the customer who was going to buy it, and a customer who found the product somewhere else often never comes back: next time they will go straight to the place that actually had it. Winning back a customer who left is more expensive and slower than keeping one who already knows your business and trusts it.

Put numbers on the problem: if a product earns you $2,000 of margin per unit and it runs out ten times a month, that is $20,000 a month that never reaches your cash register from that single item. Now multiply that by the three or four products you sell the most, and by the customers who never return. That is why the goal is not to buy little or to buy a lot: it is to buy at the right moment and in the right quantity. To achieve that you only need two figures per product: the minimum stock and the reorder point.

Step 1: find each product's average monthly consumption

Everything starts with knowing how many units actually leave each month. Take the issue records of the last three to six months for each product and calculate the monthly average. If the business has seasons —year-end holidays, back-to-school, Easter week— use at least six months or measure the consumption of the equivalent month of the previous year; an average calculated only over the quiet month will leave you without merchandise right in the busy month.

From the monthly average you get the daily consumption: divide by 30 days. Do not calculate it from memory or "by what it looks like": the figure must come from the issue records. An inventory system gives you that consumption per product in seconds; doing it by hand in a notebook also works, but only if every issue was recorded, without exceptions.

Step 2: set the minimum stock, your cushion against supplier delays

The minimum stock, also called safety stock, is the amount of product that must remain in the warehouse to cover two things: the supplier's lead time and the unexpected —a late delivery, a week of higher demand, a customer who suddenly buys in bulk. Without that cushion, any supplier delay automatically becomes an empty shelf and a lost sale.

A simple practical rule is this: minimum stock = daily consumption × supplier lead time in days × 0.5. If your supplier takes ten days to deliver and you sell three units a day, the minimum is 15 units (3 × 10 × 0.5). If the supplier is unreliable or a peak season is coming, raise the factor to 1 to have more breathing room. The formula is not sacred: it is a starting point that you adjust to the reality of each product and each supplier.

Step 3: calculate the reorder point, the number that says "time to order"

The reorder point answers the most important question in the business: at exactly what moment do I place the order? The idea is simple: when your stock reaches that number, you still have enough units left to keep selling while the new order arrives. Order too early and you pile up inventory; order too late and you run out of product.

The formula is: reorder point = (daily consumption × supplier lead time in days) + minimum stock. In other words, what you will sell while waiting for the supplier, plus the safety cushion. That number is calculated once and only reviewed when consumption or the supplier changes.

A practical example: the math in one table

So this does not stay in theory, let us look at a small warehouse with five everyday products. In the table, monthly consumption comes from the real average of issues, the delay is the lead time of each supplier, the minimum stock uses the 0.5 rule, and the reorder point adds the consumption during the waiting days plus that minimum.

Read the cooking oil row: you sell 120 units a month (4 a day) and your supplier takes 7 days. The minimum stock is 14 units. The reorder point is 42: when the system shows 42 bottles, that is the moment to order. The 28 units you will sell during the 7 waiting days are covered, and the remaining 14 are the safety cushion. The suggested order, 120 units, replaces about a month of sales without bloating the warehouse.

Notice the contrast: rice and tuna, which turn over fast, have high reorder points because they sell in volume; coffee, which sells more slowly, needs fewer units even though its supplier takes longer. Every product has its own numbers, and that is why you calculate them one by one.

Step 4: decide how much to order, and resist the "buy more, it is cheaper" trap

The reorder point tells you when to order; the order quantity tells you how much. The simplest rule: order what you sell between one order and the next. If you order weekly, order one week of consumption; if you order monthly, order the monthly consumption. That keeps the warehouse full of what turns over and empty of what does not.

Watch out for deals: buying 300 units of a product you sell 40 of a month just to take advantage of a discount is not savings, it is idle money with the risk of expiration, damage or obsolescence. A discount only pays off when the product turns over fast enough to sell before the cost of holding it eats the saving.

The slow movers: money asleep in your store

Not every product deserves the same treatment. Turnover —how many times the inventory sells in a period— separates the products that generate cash from the ones that tie it up. Review the list every month and flag everything that has not moved in 60 to 90 days: that is frozen capital. A slow mover has three paths: push it with a promotion, return it to the supplier if there is an agreement, or liquidate it. What you should never do is keep buying it "just in case": every replenishment of a slow mover makes the problem worse.

A practical rule avoids most inventory excesses: always separate replenishment from opportunity. Replenishment is the automatic purchase of a product that turns over and ran out because of normal sales: it follows the reorder point. Opportunity is a one-off supplier offer or a seasonal purchase: it is decided with a different criterion, a different budget and, ideally, a different person. When the "opportunity" offer sneaks into the replenishment order, the warehouse ends up full of products nobody asked for.

Low-stock alerts: let the system warn you before the shelf goes empty

Checking the warehouse "by eye" or trusting the manager's memory is not control: it is a lottery. With several hundred products, nobody can remember the exact level of each one. The solution is an automatic alert: the system warns you when a product's stock reaches its reorder point, and the order goes out on time, every month, without depending on someone remembering to look.

An inventory system like Kardex Tauro, built for small businesses, does exactly that: it shows you the real-time stock of every product, alerts you when a level is low and gives you turnover reports so you know which products perform and which ones are sleeping. With that information, the purchasing decision stops being a gut feeling and becomes a number.

Metrics to watch every month

• Stock-outs: if a product runs out more than two or three times a month, raise its minimum stock or negotiate shorter lead times with the supplier.
• Turnover: how many times the inventory sells per month. It rises with good replenishment buys and falls when badly calculated "opportunities" come in.
• Days of inventory: how many days of sales fit in your warehouse. Less than needed causes stock-outs; much more means idle money.
• Value in slow movers: if more than 20% of the money in inventory has not turned over in over 60 days, there is excess to release.

Put it to work this week in six steps

1. List the products that move the most money, the 20% that generates 80% of sales.
2. Calculate the average monthly consumption of each one from the last three to six months of issues.
3. Write down the real delivery time of each supplier, not the one promised in the catalog.
4. Set the minimum stock with the 0.5 rule and adjust it according to how reliable the supplier is.
5. Calculate the reorder point and define the order quantity based on how often you buy.
6. Activate low-stock alerts and review turnover once a month, separating the slow movers.

Running out of product and drowning in inventory are two sides of the same mistake: buying without numbers. Minimum stock protects you from supplier delays, the reorder point tells you when to order, the order quantity tells you how much, and the monthly turnover review releases the money sleeping in slow movers.

You do not have to guess when to order. Kardex Tauro shows you real-time stock, warns you when a product reaches its reorder point and gives you the turnover reports to buy with data instead of gut feeling. Start today: register your products, set the minimum levels and let the system tell you when it is time to order.