Imagine selling 20 units of a popular product every day. Your supplier needs five days to deliver new inventory.
One morning, you check your warehouse and discover that only 30 units remain.
You immediately place another order. However, the shipment won’t arrive for several days.
Meanwhile, customers continue purchasing the product. As a result, you may run out of stock before replenishment arrives.
This situation highlights why businesses need a reorder point.
Rather than waiting until inventory becomes critically low, a reorder point helps determine when to place the next purchase order.
In this guide, you’ll learn what a reorder point means, how it works, and why it matters for inventory management.
What Is a Reorder Point?
A reorder point (ROP) is the inventory level that triggers a new purchase or replenishment order.
It helps businesses maintain enough stock to meet expected demand while waiting for new inventory.
For example, suppose your reorder point is 150 units.
When your inventory position reaches that level, it’s time to review and place a replenishment order.
However, the reorder point doesn’t determine how many units you should purchase.
Instead, it tells you when to reorder.
The quantity you purchase depends on factors such as expected demand, supplier requirements, and your inventory policy.
Why Is the Reorder Point Important?
A well-planned reorder point supports several inventory decisions.
First, it helps reduce stockout risk.
By ordering before inventory runs out, businesses have a better chance of maintaining product availability.
Additionally, reorder points improve purchasing consistency. Employees can follow defined thresholds rather than relying on guesswork.
They also help businesses avoid unnecessary emergency orders.
However, reorder points are only effective when inventory records and demand estimates are reasonably accurate.
Reorder Point Formula
The standard formula is:
Reorder Point = Average Daily Demand × Lead Time + Safety Stock
Each component serves a different purpose.
Average Daily Demand represents the typical number of units sold or consumed per day.
Lead Time is the time between placing an order and receiving usable inventory.
Safety Stock is additional inventory held to protect against unexpected demand or supply delays.
Together, these values establish a practical replenishment threshold.
How to Calculate Point
Let’s use a simple ecommerce example.
A business sells glass bottles and wants to determine when to reorder a popular product.
Its inventory information is:
| Variable | Value |
|---|---|
| Average Daily Sales | 20 units |
| Supplier Lead Time | 5 days |
| Safety Stock | 40 units |
First, calculate expected demand during the supplier lead time.
20 × 5 = 100 units
Next, add safety stock.
100 + 40 = 140 units
Therefore, the reorder point is 140 units.
When the inventory position reaches 140 units, the business should trigger replenishment.
This threshold is designed to cover expected demand during the five-day lead time while maintaining a 40-unit buffer.
Understanding Reorder and Safety Stock
Reorder point and safety stock are closely related.
However, they serve different purposes.
The reorder point determines when a replenishment order should be placed.
Meanwhile, safety stock provides additional protection against uncertainty.
For example, a supplier may occasionally deliver later than expected.
Customer demand may also increase unexpectedly.
Safety stock helps reduce the risk of running out of inventory in these situations.
Nevertheless, excessive safety stock can increase storage costs and tie up working capital.
Therefore, businesses should review their safety stock assumptions regularly.
Reorder Point vs. Reorder Quantity
These two inventory concepts are often confused.
| Factor | Reorder Point | Reorder Quantity |
|---|---|---|
| Main Purpose | Determines when to order | Determines how much to order |
| Key Considerations | Demand, lead time, safety stock | Demand, costs, supplier requirements |
| Typical Output | Inventory threshold | Purchase quantity |
| Main Objective | Prevent stockouts | Balance replenishment needs and inventory costs |
For example, a business may have a reorder point of 140 units.
However, its preferred purchase quantity might be 500 units because of supplier packaging requirements.
The two values don’t need to be equal.
How to Set Reorder Points for Different Products
Not every product should use the same replenishment threshold.
Fast-moving products generally require more frequent monitoring.
Meanwhile, slow-moving items may need smaller inventory buffers.
Supplier lead times also matter.
A product sourced locally with a two-day lead time may require a lower reorder point than an imported product requiring several weeks.
In addition, businesses should consider seasonal demand.
For example, a product that sells quickly during holiday periods may need a temporary adjustment to its reorder point.
The goal is to match replenishment rules with actual product behavior.
Common Reorder Point Mistakes
Several mistakes can make reorder points unreliable.
Using Outdated Sales Data
Customer demand changes over time.
Therefore, reorder points based on old sales figures may no longer reflect current requirements.
Review recent sales trends and seasonal patterns regularly.
Ignoring Supplier Lead Time Changes
Delivery times aren’t always consistent.
For example, shipping delays may increase replenishment lead times.
If the reorder point remains unchanged, stockout risk may increase.
Setting Safety Stock Without Analysis
Some businesses choose safety stock quantities based entirely on intuition.
However, this can lead to unnecessary overstock or insufficient protection.
Use demand variability, supplier reliability, and service requirements to guide the decision.
Relying on Inaccurate Inventory Records
A reorder point is only useful when stock information is reliable.
If inventory records show 150 units but only 100 physically exist, replenishment decisions may be delayed.
Regular stock checks help identify these differences.
How to Manage Reorder Points in Excel
Small businesses can monitor reorder points using a spreadsheet.
A simple inventory table might include:
| SKU | Current Stock | Reorder Point | Status |
|---|---|---|---|
| BOT-250 | 180 | 140 | OK |
| JAR-100 | 90 | 120 | Reorder |
| PUMP-50 | 75 | 60 | OK |
Excel can display an automatic warning when stock reaches the reorder threshold.
For example, if current stock is in cell B2 and the reorder point is in C2, use:
=IF(B2<=C2,"Reorder","OK")This formula works as a basic alert when current stock is the quantity your business uses for replenishment decisions.
However, businesses with outstanding purchase orders should consider inventory position rather than physical stock alone.
A common calculation is:
Inventory Position = On-Hand Stock + On-Order Stock − Backorders
This helps prevent unnecessary duplicate orders.
When Should You Review Your Reorder Points?
Reorder points shouldn’t remain unchanged indefinitely.
Review them when sales patterns, supplier lead times, or inventory requirements change.
For example, a product may experience increasing demand after a successful promotion.
Alternatively, a supplier may begin offering faster delivery.
Both situations can affect the appropriate reorder threshold.
For small businesses, a monthly review may provide a useful starting point.
However, fast-moving or high-value products may require more frequent monitoring.
Final Thoughts
A reorder point helps businesses decide when to replenish inventory before stock becomes insufficient.
By combining average demand, supplier lead time, and safety stock, businesses can establish practical purchasing thresholds.
However, successful implementation requires accurate inventory records and regular reviews.
For growing ecommerce businesses, reorder points can reduce emergency purchasing and support more consistent product availability.
Good inventory planning isn’t about ordering when shelves are empty. It’s about knowing when to order before that happens.