Reorder point vs safety stock: the difference and how they work together

Safety stock and the reorder point are often mixed up because they appear in the same formula. They answer different questions. Safety stock asks how much buffer to hold for the days things go wrong. The reorder point asks when to place the next order. This guide shows how they fit together, with one worked example.

The difference at a glance

	Safety stock	Reorder point
What it is	The buffer you plan to have left when an order arrives	The stock level that triggers a new order
The question it answers	How much protection do we need?	When do we order?
It changes when	Demand or lead time becomes more or less variable, or the service level changes	Average demand, the lead time or the safety stock changes
How it is used	Inside the reorder point	Compared with the inventory position every time you review

How they fit in one formula

Reorder point = average daily demand × lead time in days + safety stock

The first part covers the demand you expect while you wait for the order. Safety stock covers the demand you did not expect, and the delivery that comes late. Get the safety stock figure from the safety stock formula, then build the rest with the reorder point formula.

A worked example

An item sells 40 units a day on average. The supplier takes 10 days. With demand and lead time both varying, the safety stock at a 95% service level comes to 146 units (worked through in our safety stock examples).

Step	Working	Result
Demand during the lead time	40 × 10	400 units
Safety stock	from the formula	146 units
Reorder point	400 + 146	546 units

When the inventory position falls to 546 units, you order. If the next 10 days go as expected, 400 units are sold and 146 are left when the order lands. On a bad week the safety stock is used, and you still do not run out.

Why the stock level looks like a saw

Plotted over time, stock falls as you sell, jumps when an order arrives, then falls again. The reorder point is the line where each order is placed. Safety stock is the floor the low points should sit just above. If the low points keep landing at zero, safety stock is too low. If they never come near it, you are holding more than you need.

Five mistakes that cause stockouts or excess

• A reorder point with no safety stock. Demand during the lead time alone runs out about half the time.
• Comparing it with stock on hand. Use the inventory position, with stock already on order counted, or you will order twice.
• Forgetting the review period. If you only check stock every week, add a week of demand: you may pass the reorder point just after a review.
• Never updating the numbers. A reorder point set two years ago reflects demand and lead times from two years ago.
• One rule for every item. “Two weeks of safety stock” protects a steady item too much and an erratic one too little.

Where min-max fits

In a min-max system the min is the reorder point, and the max is the level you order up to. The same logic applies: the min should be the demand during the lead time plus safety stock. See min-max inventory for how to set both.

Calculate both

Use the free safety stock calculator and the reorder point calculator for one item. Running out anyway? Read how to prevent stockouts.

Frequently asked questions

Is the reorder point the same as safety stock?

No. Safety stock is the buffer you plan to have left when an order arrives. The reorder point is the level that triggers the order: the expected demand during the lead time plus the safety stock.

Can the reorder point be lower than safety stock?

Not if both are set correctly, because the reorder point includes the safety stock. If yours is lower, one of the inputs is wrong or out of date.

Should I compare the reorder point with stock on hand?

Compare it with the inventory position: stock on hand plus what is on order, less what is already committed to customers. Using stock on hand alone leads to ordering twice.