Reorder Point Calculator

Estimate the inventory level at which a new order should be placed using demand, lead time and safety stock

Your result will appear here.

About the Reorder Point Calculator

Reorder point estimates the inventory level at which a new order should be placed so replenishment arrives before stock is exhausted. It combines expected demand during supplier lead time with any safety stock held as a buffer.

The calculation is most useful when demand and lead time are measured consistently. If either one is highly variable, a simple average-demand formula can understate stockout risk.

How to Use the Reorder Point Calculator

  1. Enter average demand per day or other period.
  2. Enter supplier lead time in the matching period unit.
  3. Enter safety stock if you use a separate buffer.
  4. Calculate the reorder point and compare it with the inventory position used by your ordering system.

How the Calculation Works

Basic reorder point = average demand during lead time + safety stock.

If demand is d units per day and lead time is L days, expected lead-time demand = d×L. More advanced models can derive safety stock from variability and service level rather than entering it directly.

Worked example

Reorder Point Calculator Worked Example

40 units per day, 7-day lead time, 100 units safety stock

Lead-time demand = 40×7 = 280 units. Reorder point = 280+100 = 380 units.

Result guide

Understanding Your Reorder Point Calculator Result

Reaching 380 units means the modeled inventory position has entered the replenishment trigger zone. It does not necessarily mean physical on-hand stock alone should equal the trigger if open purchase orders are included in inventory position.

Before you rely on the answer

Assumptions and Limitations

  • Demand and lead time use compatible time units.
  • Average demand is representative enough for the planning model.
  • Safety stock reflects the intended service level and variability.

Practical tip

Using This Result in Practice

Define whether your system triggers on on-hand stock or inventory position, which may include on-order stock and backorders. Using the wrong definition can cause premature or late replenishment.

Related calculations

Useful Calculations to Continue With

If you need to calculate the buffer rather than enter it directly, use the Safety Stock Calculator.

Once the reorder timing is known, use the Economic Order Quantity Calculator if you also want a cost-based order-size estimate.

Common questions

Reorder Point Calculator FAQ

What is reorder point?

The inventory level that triggers replenishment under the selected demand, lead-time and safety-stock assumptions.

Is reorder point the same as order quantity?

No. Reorder point determines when to order; order quantity determines how much to order.

Why is safety stock added?

It provides a buffer against demand or lead-time uncertainty.