Reorder Point Calculator
Calculate reorder point as average daily demand x lead time plus safety stock, then compare the trigger with current on-hand stock to see whether you should release the next PO now, watch the buffer closely, or keep normal replenishment cadence.
Reorder Point Inputs
Enter average demand, supplier lead time, and your chosen safety-stock buffer to calculate the stock level where the next PO should be released.
Quick Scenarios
Reorder Point Summary
Watch buffer
588 units
The trigger is close enough that one demand spike can erase the gap. Trigger coverage = 14 demand days.
Lead-time demand
420 units
Safety stock
168 units
Current stock gap
+132 units
Current stock coverage
17.14 days
You are still above the trigger, but only by about 3.14 days of demand. Review inbound supply, promotions, and supplier changes before the 4-day buffer window is fully used.
Exact formula output: 588 units. The rounded trigger uses 588 units, and safety stock contributes 28.6% of that trigger.
Detailed Breakdown
Safety-stock conversion
Safety stock units = average daily demand x safety-stock days
= 42 x 4
Result: 168 units
Reorder-point formula
ROP = (average daily demand x lead time) + safety stock
= (42 x 10) + 168
Result: 588 units
| Metric | Value |
|---|---|
| Average daily demand | 42 units |
| Lead time | 10 days |
| Safety-stock days | 4 days |
| Current stock | 720 units |
| Lead-time demand | 420 units |
| Safety stock | 168 units |
| Exact reorder point | 588 units |
| Rounded trigger | 588 units |
| Units above/below trigger | +132 |
| Days until reorder | 3.14 days |
Assumption notes
- Safety stock is entered as days of average demand, not as a service-level probability.
- Current stock should reflect usable on-hand units, not open POs or quarantined inventory.
- Reorder point is the release trigger, not the suggested purchase quantity.
Current scenario highlights
- Trigger coverage window: 14 days
- Current stock coverage: 17.14 days
- Status: Close watch
Editorial & Review Information
Reviewed on: 2026-03-12
Published on: 2025-09-11
Author: LumoCalculator Editorial Team
What we checked: Formula arithmetic, trigger logic, example math, boundary statements, and source accessibility.
Purpose and scope: This page supports SKU-level replenishment planning and manual reorder reviews. It does not replace ERP master data, MOQ rules, supplier contracts, or multi-echelon inventory policy.
How to use this review: Keep demand and lead-time units aligned, convert buffer policy into a realistic number of days, and compare the trigger with usable on-hand stock before releasing a purchase order.
Use Scenarios
Buyer daily review
Turn one SKU's demand rate, lead time, and chosen buffer into a clear reorder trigger for a morning purchasing review instead of relying on a rough gut check.
Buffer policy handoff
Use this page when the safety-stock policy is already decided, then compare the buffer-setting side with the Safety Stock Calculator if the real question is how large the buffer should be.
Stock-gap escalation
Compare current usable stock with the trigger after a promotion, supplier slip, or demand step change so the team can decide whether normal replenishment still works or an expedite is required.
Formula Explanation
1) Lead-time demand
Lead-time demand = average daily demand x lead time
This is the stock you expect to consume while the supplier is filling and shipping the next order. It is the base replenishment need before any protective buffer is added.
2) Safety-stock conversion
Safety stock units = average daily demand x safety-stock days
This page treats safety stock as a policy expressed in days of demand. That makes the trigger easy to explain operationally, but it also means the calculator is only as good as the buffer policy you entered.
3) Reorder point
Reorder point = lead-time demand + safety stock
The result is the inventory level where the next order should be triggered. In demand-day terms, the trigger covers lead time plus the additional safety-stock window.
4) Trigger is not order quantity
Reorder point answers when to order, not how much to order
Teams often confuse the trigger with the purchase quantity. If the quantity decision is still open, compare this result with the EOQ Calculator or your supplier MOQ rules instead of using one number for both timing and quantity.
How to Read the Result
Reorder now
If current usable stock is at or below the trigger, the buffer is already being consumed. The operational question shifts from timing to supplier confirmation and transport reliability.
Close watch
A positive stock gap can still be fragile if only a few days of demand remain above the trigger. This is often where one promotion, delay, or forecast miss changes the action quickly.
Current stock coverage
Coverage days translate the current stock count into time. Comparing current coverage with trigger coverage is usually easier to explain in buyer or planner meetings than comparing raw unit counts alone.
Rounded versus exact trigger
Inventory actions usually happen in whole units, so the final trigger is rounded up. The exact formula output is still shown so the team can see whether pack-size rounding is materially changing the practical action level.
Example Cases
Case 1: Regional retail staple
Inputs
- Average demand: 42 units/day
- Lead time: 10 days
- Safety stock: 4 days
- Current stock: 720 units
Computed Results
- Lead-time demand: 420 units
- Safety stock: 168 units
- Reorder point: 588 units
- Gap above trigger: 132 units
Interpretation
The SKU is still above the trigger, but only by about 3.1 demand days. That is workable for a stable lane, not for a new promotion or supplier slip.
Decision Hint
Keep the PO in the normal cycle, but confirm forecast changes before the next buyer review.
Case 2: Import accessories lane
Inputs
- Average demand: 65 units/day
- Lead time: 18 days
- Safety stock: 8 days
- Current stock: 1,500 units
Computed Results
- Lead-time demand: 1,170 units
- Safety stock: 520 units
- Reorder point: 1,690 units
- Gap below trigger: -190 units
Interpretation
The lane is already below the trigger, so the issue is no longer whether to reorder. The issue is whether inbound timing and supplier capacity are still realistic.
Decision Hint
Release the order now and review whether the 8-day buffer is still enough for this import lane.
Case 3: Critical spare parts shelf
Inputs
- Average demand: 8 units/day
- Lead time: 30 days
- Safety stock: 12 days
- Current stock: 350 units
Computed Results
- Lead-time demand: 240 units
- Safety stock: 96 units
- Reorder point: 336 units
- Days until reorder: 1.75 days
Interpretation
The stock gap is positive, but only barely. With a long lead time and critical service promise, the trigger is effectively imminent.
Decision Hint
Treat the SKU as a close-watch item and release the order at the next review unless demand softens immediately.
Boundary Conditions
Sources & References
- Zoho Inventory - Reorder Point Calculator - Calculator-first framing, trigger definition, and operational explanation of reorder point versus safety stock.
- Omni Calculator - Reorder Point Calculator - Plain-language input definitions, inventory-replenishment framing, and quick-formula intent.
- Bloom Group - Reorder Point Formula & Calculator - Deeper discussion of formula usage, lead-time and safety-stock assumptions, and common reorder point problems.