Inventory reorder-point calculator
Enter your average daily demand, the lead time in days and your safety stock to see the stock level at which you should place a new order, before what you have runs out. Knowing your reorder point helps you avoid stockouts while you wait for the supplier.
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How to use it
- Enter how many units of this product you sell on an average day.
- Enter the lead time: the days from sending the order to your supplier until the goods are ready to sell.
- Enter your safety stock in units, or choose to derive it from the highest daily demand and the longest lead time you have seen.
- Read the reorder point and its parts: demand during lead time and safety stock.
Example
Daily demand of 40 units, a lead time of 7 days and safety stock of 100 units: demand during lead time is 40 × 7 = 280 units.
The reorder point is 280 + 100 = 380 units: place a new order when stock falls to 380 units.
Limits and caveats
- The result is a planning estimate, not a demand forecast: the tool assumes a constant average daily demand and a fixed lead time. It does not model seasonality, promotions or sales trends.
- It handles one product at a time and does not calculate the order quantity (EOQ), supplier minimum orders or holding costs.
- Compare the reorder point with stock on hand plus quantities already ordered and not yet received. The tool does not know your current stock.
- The "maximum minus average" safety stock is a simple rule based on the worst case you have seen. It is not a statistical service-level calculation.
- Parts are rounded to two decimals and then added, so the numbers on screen always add up to the result. The largest accepted value per field is 1,000,000,000.
Questions about this tool
What does the reorder point mean?
It is the stock level at which you send a new purchase order. It equals what you will sell while waiting for delivery (daily demand × lead time) plus the safety stock that covers a late supplier or a jump in sales.
How do I choose the safety stock?
If you know the number, type it in. Otherwise choose "Derive from maximums": highest daily demand × longest lead time − average demand × average lead time. It is a cautious rule that covers the worst case you have seen, and it can give more stock than you need.
Why is my reorder point equal to the safety stock?
That happens when daily demand is zero or lead time is zero, so nothing is consumed while you wait for delivery. The tool explains this in a note under the result so you can check your inputs.
How do I calculate the reorder point?
Reorder point = average daily demand × lead time in days + safety stock. Selling 25 units a day with a 10-day lead time and 50 units of safety stock gives 25 × 10 + 50 = 300 units, so place a new order when your stock falls to 300.
What is the difference between the reorder point and the order quantity?
The reorder point tells you when to order; the order quantity tells you how much. This reorder point calculator works out the first only and does not calculate the economic order quantity (EOQ), so choose the quantity from your sales, the supplier’s minimum order and your storage space.