Act on the result
Compare inventory position with the reorder point and confirm open orders before placing a new purchase order.
Educational only: Business decision support, not accounting, tax or legal advice.
Privacy: No account is required. Tool inputs and results stay in this browser. Anonymous categorical usage analytics send only governed page, tool, cluster and action identifiers; tool inputs and results are never sent. Error monitoring is disabled. Optional saved state stays only on this device.
Update policy: Reviewed when formulas or official dependencies change.
Scope: Market-neutral small-business planning using your own assumptions.
What this planner helps you decide
Best for
Inventory operators deciding when an item needs replenishment.
Outputs
Lead-time demand, safety stock, reorder point, inventory position and days of cover.
Start here
Use measured daily demand and supplier lead time, then choose the safety-stock method.
Use a different tool when: Do not use this to measure inventory turnover and target working-capital change; use Inventory Turnover Planner for that decision. Use this tool to set an inventory reorder point from demand and lead-time risk.
Commerce & operations
Reorder Point: lead-time demand
Lead-time demand, safety stock, reorder point, inventory position and days of cover.
Amounts use the same currency as your inputs. No currency conversion is performed.
Reorder Point
Set a reorder point from demand, lead time, safety stock and the current inventory position.
Your numbers stay in this browser
Choose a days-of-demand allowance or a statistical demand-and-lead-time model.
Use average units consumed or sold per day.
Use elapsed days from ordering to stock availability.
Extra days of average demand held as protection.
Use measured daily demand variability for the same item.
Use measured supplier lead-time variability in days.
Enter the service factor approved for your stock policy; 1.645 is approximately 95%.
Count available units now.
Include open purchase orders expected to arrive.
Include committed units not yet fulfilled.
Decision result
Every value is bound to the registered inventory or hospitality engine and keeps the decision components visible on one consistent basis.
- Lead Time Demand
- 400 units
- Safety Stock
- 200 units
- Reorder point
- 600 units
- Inventory Position
- 580 units
- Order Alert
- 1 units
- Quantity Below Reorder Point
- 20 units
- Days Cover
- 14.5 days
Statistical safety-stock method
Use measured demand and lead-time variability to test a user-selected service factor. This method belongs to the Reorder Point Planner and has no standalone route.
- Statistical safety-stock units
- 10.77 units
- Equivalent safety-stock days
- 1.08 days
- Safety-stock investment
- 53.85
Calculation details
View calculation detailsView the formulas and inputs used for these results.
Statistical safety-stock units
Statistical safety-stock units
z × sqrt(lead time × demand variance + average demand² × lead-time variance)10.77 unitsResult10.77 units
Uses only the six editable assumptions in this embedded reorder-point module. The exact engine retains raw precision; display rounding does not feed calculation.
Statistical safety-stock module formulas →Inputs used by these formula steps
- Statistical safety-stock unitsModule Average Daily Demand
- 10
- Statistical safety-stock unitsModule Demand Standard Deviation Per Day
- 2
- Statistical safety-stock unitsModule Average Lead Time Days
- 4
- Statistical safety-stock unitsModule Lead Time Standard Deviation Days
- 1
- Statistical safety-stock unitsModule Service Factor ZScore
- 1
- Statistical safety-stock unitsModule Unit Inventory Cost
- 5
Equivalent safety-stock days
Equivalent safety-stock days
safety-stock units / average daily demand1.08 daysResult1.08 days
Uses only the six editable assumptions in this embedded reorder-point module. The exact engine retains raw precision; display rounding does not feed calculation.
Statistical safety-stock module formulas →Inputs used by these formula steps
- Equivalent safety-stock daysModule Average Daily Demand
- 10
- Equivalent safety-stock daysModule Demand Standard Deviation Per Day
- 2
- Equivalent safety-stock daysModule Average Lead Time Days
- 4
- Equivalent safety-stock daysModule Lead Time Standard Deviation Days
- 1
- Equivalent safety-stock daysModule Service Factor ZScore
- 1
- Equivalent safety-stock daysModule Unit Inventory Cost
- 5
Safety-stock investment
Safety-stock investment
safety-stock units × unit inventory cost53.85Result53.85
Uses only the six editable assumptions in this embedded reorder-point module. The exact engine retains raw precision; display rounding does not feed calculation.
Statistical safety-stock module formulas →Inputs used by these formula steps
- Safety-stock investmentModule Average Daily Demand
- 10
- Safety-stock investmentModule Demand Standard Deviation Per Day
- 2
- Safety-stock investmentModule Average Lead Time Days
- 4
- Safety-stock investmentModule Lead Time Standard Deviation Days
- 1
- Safety-stock investmentModule Service Factor ZScore
- 1
- Safety-stock investmentModule Unit Inventory Cost
- 5
Inputs used
- Average daily demand
- 10
- Daily demand standard deviation
- 2
- Average lead time
- 4
- Lead-time standard deviation
- 1
- Service factor (z-score)
- 1
- Unit inventory cost
- 5.00
Scenario comparison
Each row names the assumption axis changed from the baseline.
ScenarioResultDifference
Current scenario600 unitsBaseline
Lower Supplier lead time560 units-40 units
Higher Supplier lead time640 units40 units
Save these results, change an input, then compare the updated figures with this baseline.
The baseline is temporary in this tab and is not added to shared scenario links or generated reports.
Calculation details
View calculation detailsView the formulas and inputs used for these results.
Lead Time Demand
Lead Time Demand
average daily demand × lead time days400 unitsResult400 units
Uses one consistent period, item basis and market-neutral ex-tax currency where money applies. The engine retains full precision; display rounding does not feed calculation.
Reorder Point Planner formulas →Inputs used by these formula steps
- Lead Time DemandMethod
- 0
- Lead Time DemandAverage Daily Demand
- 40
- Lead Time DemandLead Time Days
- 10
- Lead Time DemandSafety Stock Days
- 5
- Lead Time DemandDemand Standard Deviation Per Day
- 8
- Lead Time DemandLead Time Standard Deviation Days
- 2
- Lead Time DemandService Factor ZScore
- 1.64
- Lead Time DemandCurrent Stock
- 500
- Lead Time DemandOn Order
- 100
- Lead Time DemandBackorders
- 20
Safety Stock
Safety Stock
selected safety-stock method200 unitsResult200 units
Uses one consistent period, item basis and market-neutral ex-tax currency where money applies. The engine retains full precision; display rounding does not feed calculation.
Reorder Point Planner formulas →Inputs used by these formula steps
- Safety StockMethod
- 0
- Safety StockAverage Daily Demand
- 40
- Safety StockLead Time Days
- 10
- Safety StockSafety Stock Days
- 5
- Safety StockDemand Standard Deviation Per Day
- 8
- Safety StockLead Time Standard Deviation Days
- 2
- Safety StockService Factor ZScore
- 1.64
- Safety StockCurrent Stock
- 500
- Safety StockOn Order
- 100
- Safety StockBackorders
- 20
Reorder point
Reorder Point
lead-time demand + safety stock600 unitsResult600 units
Uses one consistent period, item basis and market-neutral ex-tax currency where money applies. The engine retains full precision; display rounding does not feed calculation.
Reorder Point Planner formulas →Inputs used by these formula steps
- Reorder PointMethod
- 0
- Reorder PointAverage Daily Demand
- 40
- Reorder PointLead Time Days
- 10
- Reorder PointSafety Stock Days
- 5
- Reorder PointDemand Standard Deviation Per Day
- 8
- Reorder PointLead Time Standard Deviation Days
- 2
- Reorder PointService Factor ZScore
- 1.64
- Reorder PointCurrent Stock
- 500
- Reorder PointOn Order
- 100
- Reorder PointBackorders
- 20
Inventory Position
Inventory Position
stock on hand + on order − backorders580 unitsResult580 units
Uses one consistent period, item basis and market-neutral ex-tax currency where money applies. The engine retains full precision; display rounding does not feed calculation.
Reorder Point Planner formulas →Inputs used by these formula steps
- Inventory PositionMethod
- 0
- Inventory PositionAverage Daily Demand
- 40
- Inventory PositionLead Time Days
- 10
- Inventory PositionSafety Stock Days
- 5
- Inventory PositionDemand Standard Deviation Per Day
- 8
- Inventory PositionLead Time Standard Deviation Days
- 2
- Inventory PositionService Factor ZScore
- 1.64
- Inventory PositionCurrent Stock
- 500
- Inventory PositionOn Order
- 100
- Inventory PositionBackorders
- 20
Quantity Below Reorder Point
Quantity Below Reorder Point
max(0, reorder point − inventory position)20 unitsResult20 units
Uses one consistent period, item basis and market-neutral ex-tax currency where money applies. The engine retains full precision; display rounding does not feed calculation.
Reorder Point Planner formulas →Inputs used by these formula steps
- Quantity Below Reorder PointMethod
- 0
- Quantity Below Reorder PointAverage Daily Demand
- 40
- Quantity Below Reorder PointLead Time Days
- 10
- Quantity Below Reorder PointSafety Stock Days
- 5
- Quantity Below Reorder PointDemand Standard Deviation Per Day
- 8
- Quantity Below Reorder PointLead Time Standard Deviation Days
- 2
- Quantity Below Reorder PointService Factor ZScore
- 1.64
- Quantity Below Reorder PointCurrent Stock
- 500
- Quantity Below Reorder PointOn Order
- 100
- Quantity Below Reorder PointBackorders
- 20
Days Cover
Days Cover
max(0, inventory position) / average daily demand14.5 daysResult14.5 days
Uses one consistent period, item basis and market-neutral ex-tax currency where money applies. The engine retains full precision; display rounding does not feed calculation.
Reorder Point Planner formulas →Inputs used by these formula steps
- Days CoverMethod
- 0
- Days CoverAverage Daily Demand
- 40
- Days CoverLead Time Days
- 10
- Days CoverSafety Stock Days
- 5
- Days CoverDemand Standard Deviation Per Day
- 8
- Days CoverLead Time Standard Deviation Days
- 2
- Days CoverService Factor ZScore
- 1.64
- Days CoverCurrent Stock
- 500
- Days CoverOn Order
- 100
- Days CoverBackorders
- 20
Order Alert
Order Alert
1 when inventory position is at or below reorder point; otherwise 01 unitsResult1 units
Uses one consistent period, item basis and market-neutral ex-tax currency where money applies. The engine retains full precision; display rounding does not feed calculation.
Reorder Point Planner formulas →Inputs used by these formula steps
- Order AlertMethod
- 0
- Order AlertAverage Daily Demand
- 40
- Order AlertLead Time Days
- 10
- Order AlertSafety Stock Days
- 5
- Order AlertDemand Standard Deviation Per Day
- 8
- Order AlertLead Time Standard Deviation Days
- 2
- Order AlertService Factor ZScore
- 1.64
- Order AlertCurrent Stock
- 500
- Order AlertOn Order
- 100
- Order AlertBackorders
- 20
Inputs used
- Safety-stock method
- 0
- Average daily demand
- 40
- Supplier lead time
- 10
- Safety-stock days
- 5
- Daily demand standard deviation
- 8
- Lead-time standard deviation
- 2
- Service factor (z-score)
- 1.64
- Stock on hand
- 500
- Stock already on order
- 100
- Backorders
- 20
Open this calculator with preset values
This calculator supports documented, shareable scenario URLs. Compatible assistants and applications can construct links using the parameters below.
Scenario links contain only allowlisted numeric and closed-choice inputs shown in the URL; Margin101 excludes free text and identifying fields. Anyone you share the URL with can read those numbers, so do not include private or identifying data.
| Parameter | Meaning | Unit | Allowed values | Presence | Default |
|---|---|---|---|---|---|
| averageDailyDemand | Use average units consumed or sold per day. | product units/day | 0 to 100000000 | Required | 40 |
| backorders | Include committed units not yet fulfilled. | whole product units | 0 to 100000000 | Required | 20 |
| currentStock | Count available units now. | whole product units | 0 to 100000000 | Required | 500 |
| demandStandardDeviationPerDay | Use measured daily demand variability for the same item. | product units/day | 0 to 100000000 | Required | 8 |
| leadTimeDays | Use elapsed days from ordering to stock availability. | days | 0 to 3660 | Required | 10 |
| leadTimeStandardDeviationDays | Use measured supplier lead-time variability in days. | days | 0 to 3660 | Required | 2 |
| method | Choose a days-of-demand allowance or a statistical demand-and-lead-time model. | — | 0 (Safety-stock days), 1 (Statistical service factor) | Required | Safety-stock days |
| onOrder | Include open purchase orders expected to arrive. | whole inbound product units | 0 to 100000000 | Required | 100 |
| safetyStockDays | Extra days of average demand held as protection. | days | 0 to 3660 | Required | 5 |
| serviceFactorZScore | Enter the service factor approved for your stock policy; 1.645 is approximately 95%. | standard deviations above mean demand | 0 to 5 | Required | 1.644853626951 |
Reorder Point: lead-time demand
Treat the reorder point as an operating trigger based on the entered demand, lead time and protection level.
Formula summary
- Primary formula
- lead-time demand + safety stock
Data used here
- The estimate uses your inputs and the general business formula documented in the methodology.
Decision checks
Stress-test the decision
Retest longer lead time and higher demand variability before reducing safety stock.
When this estimate can be misleading
- Demand, costs, lead times, tax and targets are user-entered scenarios; no market benchmark is embedded.
- Use one consistent item, period and ex-tax currency basis where money applies.
- This is educational business decision support, not accounting, tax, legal or financial advice.
- Treat the reorder point as an operating trigger based on the entered demand, lead time and protection level.
Educational estimate, not advice. See all assumptions & limitations →
Related reading
Guides to interpret the decision and its assumptions.
- Inventory Turn vs Stock Availability
Compare stock efficiency and availability on aligned periods without prescribing a universal turn or service target.
Read guide
Frequently asked questions
How do I set an inventory reorder point from demand and lead-time risk?
Compare inventory position with the reorder point and confirm open orders before placing a new purchase order.
Which planning assumptions should I stress-test?
Compare a plausible alternative scenario and verify the decision-critical assumption that changes the plan most.