Reorder Point Planner methodology

leadTimeDemand = average daily demand × lead time days

safetyStock = selected safety-stock method

reorderPoint = lead-time demand + safety stock

inventoryPosition = stock on hand + on order − backorders

quantityBelowReorderPoint = max(0, reorder point − inventory position)

daysCover = max(0, inventory position) / average daily demand

orderAlert = 1 when inventory position is at or below reorder point; otherwise 0

SS = z × sqrt(L × sigmaD² + D² × sigmaL²)

SSdays = SS / D

SSinvestment = SS × unit inventory cost

Money inputs and outputs use the currency selected in the scenario without changing the canonical methodology. Rates, margins, utilisation and buffers are entered as percentages and converted to decimal values for calculation.

• All values must be finite and inside the visible validation boundaries.
• Rates are entered as percentages and calculations retain decimal precision.
• Money and operational records use one consistent period and basis.
• The statistical safety-stock method rejects a service factor above five. It reports raw expected units; apply any whole-unit purchasing rounding separately and disclose that operational choice.

Safety-stock method minimum

method ≥ 0 — A lower value is rejected before calculation.

Safety-stock method maximum

method ≤ 1 — A higher value is rejected before calculation.

Average daily demand minimum

averageDailyDemand ≥ 0 product units/day — A lower value is rejected before calculation.

Average daily demand maximum

averageDailyDemand ≤ 100,000,000 product units/day — A higher value is rejected before calculation.

Supplier lead time minimum

leadTimeDays ≥ 0 days — A lower value is rejected before calculation.

Supplier lead time maximum

leadTimeDays ≤ 3,660 days — A higher value is rejected before calculation.

Safety-stock days minimum

safetyStockDays ≥ 0 days — A lower value is rejected before calculation.

Safety-stock days maximum

safetyStockDays ≤ 3,660 days — A higher value is rejected before calculation.

Daily demand standard deviation minimum

demandStandardDeviationPerDay ≥ 0 product units/day — A lower value is rejected before calculation.

Daily demand standard deviation maximum

demandStandardDeviationPerDay ≤ 100,000,000 product units/day — A higher value is rejected before calculation.

Lead-time standard deviation minimum

leadTimeStandardDeviationDays ≥ 0 days — A lower value is rejected before calculation.

Lead-time standard deviation maximum

leadTimeStandardDeviationDays ≤ 3,660 days — A higher value is rejected before calculation.

Service factor (z-score) minimum

serviceFactorZScore ≥ 0 standard deviations above mean demand — A lower value is rejected before calculation.

Service factor (z-score) maximum

serviceFactorZScore ≤ 5 standard deviations above mean demand — A higher value is rejected before calculation.

Stock on hand minimum

currentStock ≥ 0 whole product units — A lower value is rejected before calculation.

Stock on hand maximum

currentStock ≤ 100,000,000 whole product units — A higher value is rejected before calculation.

Stock already on order minimum

onOrder ≥ 0 whole inbound product units — A lower value is rejected before calculation.

Stock already on order maximum

onOrder ≤ 100,000,000 whole inbound product units — A higher value is rejected before calculation.

Backorders minimum

backorders ≥ 0 whole product units — A lower value is rejected before calculation.

Backorders maximum

backorders ≤ 100,000,000 whole product units — A higher value is rejected before calculation.

• Demand, lead times, costs, tax and targets are supplied by the user.
• No jurisdiction, supplier service level, industry benchmark or forecast is embedded.
• The engine retains full precision and display formatting never feeds back into calculation.
• The statistical method assumes the entered demand and lead-time variability are representative and does not guarantee a service level.

This planner has no current policy-data dependency. Its commercial assumptions are user supplied. Registered family-level regression suites exercise the shared business-logic engine and worked-result reconciliation.

• Results depend on the quality and timing alignment of entered records.
• The model does not replace inventory, accounting, tax, legal or financial advice.

This is educational decision support, not tax, accounting, legal or financial advice. Check the treatment of your actual transactions under the rules that apply to your business and seek qualified advice where appropriate.

Registered family-level suites test formula invariants and example reconciliation; the release ledger records that coverage without claiming a separate oracle for every line of public copy. There is no official threshold or benchmark to refresh for this planner. Commercial inputs remain user-supplied because they vary by business and contract.

1. 2026-07-16: Initial public release of the Reorder Point planner and methodology.