Inventory Reorder Point Calculator

Check inventory inputs

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SKU or item:

Use a short SKU, product, ingredient, or spare-part label.

Average daily demand:

Use the expected daily pull for this SKU, not a peak day.

{{ unitLabel }}/day

Average supplier lead time:

Include supplier processing, transit, receiving, and put-away time.

days

Inventory position:

Enter stock you can count now and confirmed units already on order.

on hand

inbound

Safety stock method:

This changes how the buffer above lead-time demand is calculated.

Target service level:

Use 95% for many normal SKUs, and higher values for critical or slow-to-recover items.

Demand variability source:

Demand standard deviation:

{{ unitLabel }}/day SD

Usual daily demand range:

min/day

max/day

Demand volatility profile:

Lead-time variability source:

Lead-time standard deviation:

days SD

Usual lead-time range:

min days

max days

Supplier reliability profile:

Manual safety stock:

Use this when your planning policy already defines the buffer in units.

Max usage and lead time:

Use realistic historical peaks; one-off outliers can overstate reorder points.

max/day

max days

Target stock coverage:

Pick how many days of demand you want covered after replenishment, before the safety stock buffer.

days

Reserved or backordered units:

Include customer backorders, production allocations, or service tickets already committed.

Pack and minimum order:

Use 1 and 0 when the supplier lets you order exact units.

pack

MOQ

Review cadence:

Set to 1 for daily review or a larger number for weekly purchasing runs.

days

Stress-test adjustments:

Tune the stress ladder used in the result artifact.

demand %

lead %

Unit label:

Metric	Value	Basis	Copy
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Check	Status	Action	Copy
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Scenario	Status	Reorder point	Gap	Action	Copy
{{ row.scenario }}	{{ row.status }}	{{ row.reorderPoint }}	{{ row.gap }}	{{ row.action }}

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Referrer policy

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A reorder point is the inventory position where a SKU should trigger replenishment. It is not just the on-hand count. It considers demand during supplier lead time, a safety-stock buffer, inbound supply, and reserved or backordered units so the buyer can act before stock reaches zero.

The core tradeoff is service versus inventory. A higher reorder point reduces stockout risk but ties up more cash and shelf space. A lower reorder point reduces stock on hand but leaves less protection when demand rises, lead time stretches, or a shipment arrives late.

Reorder point as lead-time demand plus safety stock compared with inventory position — The trigger is reached when inventory position falls to lead-time demand plus safety stock.

This calculator estimates a SKU reorder point from demand, supplier lead time, safety-stock policy, inventory position, pack-size rules, and a target stock level. It also stress-tests demand and lead-time changes so the trigger can be reviewed before a purchase order is created.

How to Use This Tool:

Enter the SKU or item label, average daily demand, and average supplier lead time.
Add on-hand units and inbound units. Use reserved or backordered units when committed stock should not count as available.
Select the safety-stock method. Use service level and variability when you have demand and lead-time variation, manual safety stock when policy already sets a buffer, or maximum usage when you plan from worst-case daily demand and lead time.
Set target stock coverage to describe how many days of stock you want after replenishment.
Add supplier pack size and minimum order quantity so the recommendation reflects purchasable quantities.
Use review cadence and stress-test inputs to see whether the trigger is close enough to require action before the next normal review.

Demand and lead time should be measured over a period that matches current operations. Old averages can understate risk when sales velocity, supplier performance, or promotion plans have changed.

Interpreting Results:

Reorder point is the rounded trigger level. Inventory position is on-hand plus inbound stock minus reserved or backordered units. If inventory position is at or below the reorder point, the page moves to an order-now status.

Inventory reorder point status interpretation
Status	Condition	Action
`Monitor`	Inventory position is above the reorder point beyond the review cadence.	Keep the SKU on the normal review cycle.
`Review soon`	Projected days until trigger are within the review cadence.	Check supplier availability and demand changes before the next review.
`Order now`	Inventory position is at or below the reorder point.	Create or review a purchase order using supplier rounding.
`Stockout`	Net available on-hand stock is zero or lower.	Escalate replenishment and customer commitment review.

The recommendation uses target stock coverage after the trigger and rounds to pack size and minimum order quantity. The raw target can be lower than supplier rounding, so check both the ideal quantity and the purchasable quantity.

Technical Details:

The model begins with lead-time demand, adds safety stock according to the selected policy, then compares the rounded reorder point with inventory position. Purchase quantity is calculated from target stock and rounded to supplier constraints.

Formula Core:

\begin{array}{lcl} leadTimeDemand & = & dailyDemand \times leadTimeDays \\ safetyStock & = & z \times \sqrt{leadTimeDays \times {sigma}_{demand}^{2} + {dailyDemand}^{2} \times {sigma}_{lead}^{2}} \\ reorderPoint & = & ⌈ leadTimeDemand + safetyStock ⌉ \\ inventoryPosition & = & onHand + inbound - reserved \end{array}

Safety stock method details
Method	Calculation	Best fit
Service level	Uses a service-level z score and demand and lead-time variability.	SKUs with usable history and a service target.
Manual	Uses the entered safety-stock units directly.	Policy buffers set by planners, suppliers, or managers.
Maximum usage	`max daily demand x max lead time - lead-time demand`	Simple worst-case screening when history is thin.

For order quantity, the calculator first sets a target stock level from coverage days and safety stock, then calculates the gap between target stock and inventory position. Pack-size rounding uses the next whole pack after respecting minimum order quantity.

\begin{array}{lcl} targetStock & = & max (reorderPoint, ⌈ dailyDemand \times targetCoverDays + safetyStock ⌉) \\ rawOrder & = & max (0, targetStock - inventoryPosition) \\ roundedOrder & = & ⌈ \frac{max(rawOrder, MOQ)}{packSize} ⌉ \times packSize \end{array}

Limitations and Accuracy:

Reorder point math assumes the demand and lead-time inputs describe the future reasonably well. Promotions, seasonality, supplier shutdowns, new product launches, MOQ changes, and allocation rules can make historical averages misleading.

Use the result as a replenishment planning aid, then review high-value, perishable, regulated, or customer-critical SKUs with supplier terms, service targets, and planner judgment before ordering.

Worked Examples:

Simple manual buffer. A SKU sells 12 units per day, lead time is 8 days, and manual safety stock is 30 units. Lead-time demand is 96, so reorder point is 126 units.

Inventory position check. If the same SKU has 80 on hand, 40 inbound, and 10 reserved, inventory position is 110. Because 110 is below the 126 reorder point, the SKU is already in order-now territory.

Supplier rounding. If target stock is 220 and inventory position is 110, the raw order is 110. With a pack size of 24 and MOQ of 96, the purchasable order rounds up to 120 units.

FAQ:

Is reorder point the same as minimum stock?

Not exactly. Minimum stock often describes a policy floor, while reorder point is the trigger that accounts for lead-time demand and safety stock.

Why include inbound units?

Inbound purchase orders are part of inventory position because they are already planned supply. If inbound dates are unreliable, stress-test lead time before relying on them.

Which safety-stock method should I use?

Use the service-level method when you have variability data. Use manual when policy already sets the buffer. Use maximum usage for a conservative screen with simple inputs.

Why is the recommended order larger than the gap?

Supplier pack size and minimum order quantity can force the order above the raw gap needed to reach target stock.

Glossary:

Reorder point: The inventory position where replenishment should be triggered.
Lead-time demand: Expected demand during the supplier lead time.
Safety stock: Buffer stock held for demand variation, supplier delay, or forecast error.
Inventory position: On-hand stock plus inbound supply minus reserved or backordered units.
Service level: The target probability of covering demand without stockout during the replenishment cycle.
Pack size: The supplier's purchasable multiple for the SKU.

References:

Reorder Point Planning, Oracle Inventory Help.
What is the Reorder Point?, QuickBooks.

Inventory Reorder Point Calculator

Introduction

How to Use This Tool:

Interpreting Results:

Technical Details:

Formula Core:

Limitations and Accuracy:

Worked Examples:

FAQ:

Glossary:

References: