Free reorder point calculator with safety stock

This free reorder point calculator tells you the stock level at which to place your next purchase order. Enter average daily demand, supplier lead time and either your safety stock or the variability needed to calculate it. It runs in your browser.

When to use a reorder point

A reorder point (ROP) works best for parts you buy repeatedly from a supplier with a fairly steady lead time: fasteners, packaging, raw stock and common purchased components. When on-hand plus on-order stock falls to the reorder point, you place the next order. The aim is simple: the new delivery should arrive just as you reach your safety stock, not after you run out.

It is a weaker fit for items with lumpy, project-driven demand or very long, unreliable lead times. For those, a planned order based on your production schedule (MRP) or a regular review with a planner usually works better.

How to read the result

• Lead-time demand is what you expect to use while you wait for the order to arrive.
• Safety stock is the buffer for days when demand runs high or the supplier runs late.
• Reorder point is the two added together. Compare it with on-hand plus open purchase orders, not on-hand alone.

Check the inputs before you trust the number. Use recent usage history rather than a single busy month, and use the lead time the supplier actually delivers, not the one quoted. Review the reorder point when demand, the supplier or the lead time changes. For the full method with a worked example, read our reorder point formula guide. To size the buffer itself, use the safety stock calculator.

How the reorder point is calculated

The first part is the stock you expect to use while you wait for the order to arrive. Safety stock covers the days when demand runs higher or the delivery runs late. If you choose to calculate safety stock here, the tool uses the same variable-lead-time method as our safety stock calculator.

Worked example (hypothetical numbers)

A distributor sells an average of 40 units a day of one item. The supplier takes 12 days to deliver, and the planner holds 150 units of safety stock.

• Demand during lead time: 40 × 12 = 480 units
• Reorder point: 480 + 150 = 630 units

When stock on hand plus stock already on order falls to 630 units, the planner raises a new order. The full derivation, with a spreadsheet version, is in our article on the reorder point formula.

When to recalculate

Review the reorder point whenever average demand, lead time or your target service level changes, for example after a supplier switch, a new sales channel or a seasonal shift. Items with lumpy or intermittent demand need a different approach, because averages describe them poorly.

Frequently asked questions

What is a reorder point?

The reorder point is the inventory level that triggers a new purchase order. It covers expected demand during the supplier’s lead time plus a safety stock buffer.

Should I compare the reorder point with stock on hand or inventory position?

Use inventory position: stock on hand plus open purchase orders, minus any stock already committed to customers. Comparing with stock on hand alone can cause duplicate orders.

What if I do not hold safety stock?

Enter zero. The reorder point then equals expected demand during lead time, so you would run short in roughly half of all cycles if demand varies around the average.

How is this different from the safety stock calculator?

The safety stock calculator focuses on sizing the buffer from demand and lead-time variability. This tool focuses on the order trigger and also accepts a safety stock figure you already use.

How much should I order when I reach the reorder point?

The reorder point tells you when to order, not how much. Use the EOQ calculator to size the order, and check it against supplier minimums with our guide to EOQ vs MOQ.

Related tools and guides

• Safety stock formula: three methods compared
• Inventory turnover calculator
• All free supply chain tools