1
Enter average daily sales
Type in how many units of this SKU you sell on an average day. Use the last 30 to 90 days of sales data divided by the number of days in that period.
Free Reorder Point Calculator
Calculate the exact inventory level to trigger your next purchase order
A reorder point is the on-hand inventory level at which you should place a new purchase order so a SKU does not run out before replenishment arrives. Enter your average daily sales, lead time, and safety stock and this calculator returns your reorder point plus a recommended minimum order quantity.
Reorder point calculatorInventory ROP formulaSafety stock calculatorEcommerce reorder point
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Calculate your reorder point
Enter your sales velocity and supplier lead time. Toggle advanced mode to compute statistical safety stock from demand variability.
Quick formulas
Reorder Point = (Average Daily Sales x Lead Time) + Safety Stock
Lead Time Demand = Average Daily Sales x Lead Time in Days
Statistical Safety Stock = Z x Standard Deviation x sqrt(Lead Time)
Recommended Min Order Qty = 2 x Lead Time Demand
How to use this reorder point calculator
2
Enter your supplier lead time
Add the number of days from placing a purchase order to receiving the goods in your warehouse. Include manufacturing, shipping, customs, and receiving time.
3
Set your safety stock
Enter a fixed safety stock buffer, or switch on the advanced mode and provide demand standard deviation plus a service level to compute statistical safety stock automatically.
4
Read your reorder point
The calculator instantly shows your reorder point, lead time demand, and a recommended minimum order quantity so you can place purchase orders before you run out.
Reorder point formula explained
The reorder point answers a simple operational question: how low can my on-hand inventory get before I have to place another purchase order? It blends two facts about your business.
Lead time demand
How many units you will sell while you wait for a new shipment to arrive. Calculated as average daily sales multiplied by lead time in days.
Safety stock
A buffer of extra units to absorb unexpected demand spikes or supplier delays. The advanced mode here computes it as Z x standard deviation x sqrt(lead time).
Reorder point
The sum of lead time demand and safety stock. When your inventory hits this number, place a new order to keep selling without stockouts.
Service level Z-scores
The Z-score sets how aggressively you protect against stockouts. Higher service levels mean fewer stockouts but more cash tied up in inventory.
| Service level | Z-score | Interpretation |
|---|---|---|
| 90% | 1.28 | Stockout in 1 of 10 cycles |
| 95% | 1.645 | Common ecommerce default |
| 97% | 1.88 | Higher safety, more cash tied up |
| 99% | 2.33 | High-stakes SKUs, hero products |
Explore more free tools
Combine the reorder point calculator with these other free Vibe Mart tools to cover pricing, fees, shipping, and inventory.
Reorder point calculator FAQ
Common questions about the reorder point formula, safety stock, and how reorder points fit into broader inventory management.
What is a reorder point?
A reorder point (ROP) is the inventory level at which you should place a new purchase order to replenish stock before running out. It accounts for how fast you sell, how long suppliers take to deliver, and a safety buffer for demand variability. When on-hand inventory drops to the reorder point, it is time to reorder.
What is the reorder point formula?
The basic reorder point formula is: ROP = (Average Daily Sales x Lead Time in Days) + Safety Stock. For example, if you sell 20 units per day, your supplier takes 14 days to deliver, and you keep 50 units of safety stock, your reorder point is (20 x 14) + 50 = 330 units.
How do I calculate safety stock?
A common statistical formula is: Safety Stock = Z x Standard Deviation of Daily Sales x Square Root of Lead Time. Z is the service level factor (1.28 for 90%, 1.645 for 95%, 1.88 for 97%, 2.33 for 99%). If you do not have demand variability data, a simple rule of thumb is to keep 1 to 2 weeks of average sales as buffer stock.
What is the difference between reorder point and reorder quantity?
The reorder point is when to order; the reorder quantity is how much to order. The reorder point triggers a purchase order, while the reorder quantity (often calculated using the Economic Order Quantity, or EOQ formula) determines how many units to buy each time you replenish.
How often should I update my reorder points?
Review reorder points at least quarterly, or anytime there is a meaningful change in demand, lead time, or supplier reliability. Seasonal products, new launches, and SKUs with variable supplier performance should be recalculated more frequently, ideally monthly.
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