How do you calculate a reorder point?

Multiply daily demand by lead time, then add safety stock. With 145 units/day, a 9-day lead time and 420 units of safety stock, the reorder point is 1,725 units.

What is lead-time demand?

It is the units you expect to consume while waiting for a replenishment order to arrive — here 145 units/day times 9 days, or 1,305 units.

When should I place the next order?

When stock falls to the reorder point. At 2,100 units on hand the example sits 375 units above the 1,725 trigger, about 2.6 days of demand away.

How does safety stock affect the reorder point?

It raises the trigger one-for-one. The 420-unit buffer lifts the reorder point from 1,305 (lead-time demand alone) to 1,725, guarding against demand or lead-time variability.

What is a good safety stock level?

Enough to cover variability in demand and lead time at your target service level — often set from a statistical formula. Too little risks stockouts; too much ties up cash.

Does the reorder point change if lead time increases?

Yes. A longer lead time raises lead-time demand directly, so the reorder point rises. At 12 days instead of 9, lead-time demand would jump to 1,740 units before safety stock.

Planning calculator

Reorder Point Calculator

The reorder point is the inventory level that triggers a new purchase or production order so stock arrives just before you run out. Materials planners and buyers rely on it to keep a line fed without over-ordering, because it bakes both expected lead-time demand and a safety-stock buffer into one threshold. Get it right and you avoid both stockouts that idle an assembly cell and the carrying cost of sitting on excess. It is the everyday lever that turns a demand forecast and a supplier lead time into a concrete "order now" signal on the MRP screen.

What this calculator does

Calculate reorder point from daily demand, lead time, safety stock, and current inventory.
Use to decide when an item should be replenished before stockout risk increases.
It computes the reorder point as lead-time demand (daily demand times lead time) plus safety stock, and tells you how far current stock sits above that trigger.

Formula used

Lead-time demand = daily demand × lead time
Reorder point = lead-time demand + safety stock
Inventory gap = current inventory − reorder point

Inputs explained

Daily demand: undefined
Lead time: undefined
Safety stock: undefined
Current inventory: undefined

How to use the result

Use it when setting or auditing reorder triggers in an MRP/ERP system, or when a supplier's lead time or demand rate changes.
It assumes constant daily demand and a fixed lead time; if either varies significantly, the fixed safety stock here may not give the service level you need.

Current U.S. benchmarks

U.S. manufacturing runs at 75.6% of capacity (Federal Reserve, May 2026). New factory orders are up 2.3% year over year (Census).

Common questions

How do you calculate a reorder point? Multiply daily demand by lead time, then add safety stock. With 145 units/day, a 9-day lead time and 420 units of safety stock, the reorder point is 1,725 units.
What is lead-time demand? It is the units you expect to consume while waiting for a replenishment order to arrive — here 145 units/day times 9 days, or 1,305 units.
When should I place the next order? When stock falls to the reorder point. At 2,100 units on hand the example sits 375 units above the 1,725 trigger, about 2.6 days of demand away.
How does safety stock affect the reorder point? It raises the trigger one-for-one. The 420-unit buffer lifts the reorder point from 1,305 (lead-time demand alone) to 1,725, guarding against demand or lead-time variability.
What is a good safety stock level? Enough to cover variability in demand and lead time at your target service level — often set from a statistical formula. Too little risks stockouts; too much ties up cash.

Last reviewed 2026-05-12.