Minimum Stock and Reorder Points: How to Avoid Stockouts Without Tying Up Capital

On Saturday morning the cooking oil shelf at your shop is empty. A few customers walk in, look at the shelf, and leave for the shop next door. The supplier arrives in the afternoon, but the sales are already gone. In another corner of your storeroom, instant noodles are stacked so high that the boxes are collecting dust. These two opposite problems usually come from the same gap: you do not have a clear minimum stock and reorder point.

Many owners order by feel. When the shelf looks full, they hold back. When it looks empty, they order everything at once. The result is uneven cash flow: sometimes too much money sleeps in the storeroom, sometimes sales disappear because the item is not there. This article shows how to calculate both numbers with a simple example you can repeat using your own shop figures.

Minimum stock and reorder point are not the same number

Minimum stock is your safety floor. It is the quantity you want to keep on the shelf or in the storeroom to absorb demand swings and supplier delays. In this example, minimum stock is also called safety stock.

Reorder point is the level that tells you to order again. It is higher than minimum stock because you still need to cover demand while waiting for delivery. The formula is: (average daily sales × lead time) + minimum stock.

Example: cooking oil sells an average of 20 bottles per day. The supplier usually needs 3 calendar days from order to delivery. You set minimum stock at 2 days of sales. Minimum stock = 20 × 2 = 40 bottles. Demand during the wait = 20 × 3 = 60 bottles. Reorder point = 60 + 40 = 100 bottles.

This means that when your stock record shows 100 bottles, do not wait for the shelf to empty. Order now. During the 3-day wait, you sell about 60 bottles, so the delivery arrives when roughly 40 bottles remain. That 40 is not a lucky leftover; it is the buffer you deliberately keep.

Minimum stock answers “how low must never become empty”. Reorder point answers “when do I call the supplier”.

How to calculate it with numbers you can repeat

Suppose you order 140 bottles each time, enough for 7 days of sales. After delivery, maximum stock is about 40 + 140 = 180 bottles, or about 9 days of sales. Your average stock is roughly 140 ÷ 2 + 40 = 110 bottles. This number is useful for calculating tied-up capital.

The purchase price is Rp16,500 per bottle. The selling price is Rp19,000, so gross margin is Rp2,500 per bottle. With an average of 110 bottles, capital tied up in stock is about 110 × Rp16,500 = Rp1,815,000. That does not include shelving, electricity, or the risk of leakage.

Compare that with ordering once a month. Monthly demand is 20 × 30 = 600 bottles. Average stock becomes 600 ÷ 2 + 40 = 340 bottles. Tied-up capital is 340 × Rp16,500 = Rp5,610,000. The difference is Rp5,610,000 − Rp1,815,000 = Rp3,795,000.

If your capital and storage cost is equivalent to 12 percent per year, that Rp3,795,000 difference costs about Rp3,795,000 × 12% ÷ 12 = Rp37,950 per month. Owners often ignore this because it never appears as an invoice. Yet the Rp3,795,000 could buy other fast-moving items or serve as a cash reserve.

Why squeezing stock too far is also expensive. Overstocking is not the only mistake. A stockout also has a price. If cooking oil is out of stock for 2 days, lost sales are about 20 × 2 = 40 bottles. At a margin of Rp2,500, lost gross profit is 40 × Rp2,500 = Rp100,000.

Compare that with the Rp37,950 monthly storage saving above. One 2-day stockout already wipes out more than twice that saving. It does not include disappointed customers who never come back. This is why cutting stock must be done by ordering more often and improving records, not by letting the shelf go empty.

There is also a cost that is hard to measure: a customer who comes specifically for one item and then buys all their groceries at another shop. The loss is not just the one bottle that was not sold, but the customer's whole basket. That is why the reorder point should be calculated for important items, not only for the shop as a whole.

Different items need different reorder points

Do not use one number for every item. UHT milk, for example, sells 6 cartons per day. Lead time is 7 calendar days because it is ordered from an out-of-town distributor. You give it 3 days of minimum stock. Minimum stock is 6 × 3 = 18 cartons, demand during the wait is 6 × 7 = 42 cartons, and the reorder point is 42 + 18 = 60 cartons.

Notice that the milk reorder point of 60 cartons looks smaller than the cooking oil reorder point of 100 bottles, even though its lead time is longer. The reason is lower daily sales. So do not compare raw numbers across items; compare days of cover.

For perishable goods such as bread or vegetables, lead time and minimum stock must be shorter. Piling up perishables is not a saving; it is a guaranteed waste. For durable, high-priced goods such as electronics, the reorder point can be lower, but the decision to hold stock must weigh tied-up capital and the risk of an old model.

Practical steps for your shop

• 1. Record daily sales per item for at least 30 days. Do not record only total revenue. Separate important items or at least important item groups. This record is the basis for every number below.
• 2. Calculate average daily sales. Divide sales over 30 days by 30. If your data is incomplete, use the most normal week, not the busiest day.
• 3. Measure actual lead time. Count from the day you send the order until the goods are ready to sell. Do not use the supplier's promise. If the supplier is often late, use a reasonable longest lead time, not the best average.
• 4. Set minimum stock in days, then convert it to units. For stable items, start with 2 days. For items with changeable demand or unreliable suppliers, consider 3 to 7 days. Minimum stock = daily sales × safety days.
• 5. Calculate the reorder point. Multiply daily sales by lead time, then add minimum stock. Write the number on the stock card, not in your head.
• 6. Set a sensible order quantity. The weekly order of 140 bottles above keeps capital light. If a supplier offers a lower price for a large purchase, compare the price saving with extra storage cost and the risk of damage.
• 7. Check physical stock against records every week. Count goods on the shelf and in the storeroom, then match them with the record. Small unchecked differences will make the reorder point wrong, because the next decision is based on the wrong number.

Common mistakes that make the calculation useless

• Using the supplier's promised lead time instead of the actual arrival record.
• Calculating average sales from the busiest month, then feeling disappointed in a normal month.
• Forgetting to subtract stock that has been ordered but has not arrived. Goods in transit still reduce the next order requirement.
• Treating display stock as uncounted. Everything on the front shelf and in the storeroom is the same stock.
• Ordering every item on the same day. This piles up cash outflows and crowds the storeroom, even though items sell at different speeds.
• Recording stock only when an item runs out. Without a daily record, the reorder point is only theory.
• Assuming minimum stock is the same as the reorder point, so the order arrives too late.

When to ask an accountant

For a shop with few items and regular suppliers, the method above is usually enough. Consider asking an accountant when you carry hundreds of items and turnover is hard to monitor, when you hold consignment stock, when you run several branches, when inventory is a large part of your balance sheet, or when you are applying for credit that requires financial statements.

An accountant also helps when inventory value must be calculated for the income statement and tax. A valuation error can shift profit from one period to another even when cash has not changed. For internal decisions, you do not need to wait for a formal report; a simple, consistent stock record is far better than a neat record prepared once a year.

Start with one stock card, not a complicated app

You do not need an expensive system to begin. One card per item is enough: date, opening stock, goods in, goods out, balance, and reorder point. When the columns are tidy, you can see which items are approaching the limit before the shelf is empty.

The Inventory Control Template from SME Finance Kit gives you a ready-to-use format for recording stock in and out, calculating balances, and marking reorder points. It is a working tool, not an accounting service; the stock decision remains yours.

To make the daily sales figures behind the calculation more reliable, read how to record daily sales. To make sure each item's margin is correct before you set a reorder point, see how to calculate unit cost and price.

Frequently asked questions

Is minimum stock the same as the reorder point?

No. Minimum stock is the buffer you do not want to exhaust, while the reorder point is the stock level at which you must place an order. The reorder point is always higher because it includes demand during the delivery wait.

How many days of minimum stock is safe?

No single number works for every business. The 2 days in this article is only an assumption for an item with stable demand and an on-time supplier. Start from your own sales and lead-time data, then raise it if you frequently run out.

What if the supplier is often late?

Use a reasonable longest lead time, not the fastest one. If delays are frequent, add minimum stock or find a backup supplier. Calculating with a promise the supplier never keeps only moves the problem to an empty shelf.

Does every item need a reorder point?

No. Focus on items that sell often, carry an important margin, or are hard to find when they run out. Very slow-moving items may be monitored more simply, as long as you still record them.

How do I count stock on the shelf and in the storeroom?

Treat both as one stock pool. Before ordering, count the physical units on the front shelf and in the storeroom, then subtract goods already ordered but not yet received. A record that counts only the storeroom will make you order too much.

When should the reorder point be recalculated?

When daily sales clearly change, lead time shifts, purchase price changes, or you add a branch. Recalculate after holidays and peak seasons too, because sales patterns usually do not return exactly to the old level.