Minimum Opening Stock Calculator

Worked example

A warehouse can estimate the minimum stock needed before confirmed receipts arrive. Check within-interval receipt timing when a shipment lands after demand must be served.

A fictional three-interval schedule needs 35 crates at the start. The largest cumulative shortage occurs in interval two, before a later receipt arrives.

Try it yourself

The calculator opens with the fictional example already filled in. Change one input, choose Calculate locally, and compare the result to the original values below. Use Reset fictional fixture to start over.

An unknown result means the available inputs do not support a value. Check the calculator’s Warnings tab for what is missing or uncertain.

Minimum opening stock 35 crates
Ending stock at the minimum opening amount 20 crates
First interval that requires the full buffer 2 interval

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Calculator

Approach (label only)Changing the label does not improve capacity, speed, error rates or confidence. Enter measured differences explicitly.

Comparison conditions and human review

Equal-resource comparison conditionsRecord budget, staffing, resources, information release dates, scenario conditions and evaluation criteria. Material differences can make options not comparable.

Evaluation period

Geography / exercise boundary

Human reviewers and roles

This evaluation depends on a real transaction

Supplied human authority gateThis declaration is not legal certification. Blocked, pending or assumed gates stop transaction-dependent evaluation.

Keep units consistent within each table. Enter zero when the amount is known to be zero. Leave optional amounts blank when they are unknown. If a required value is missing, the calculator will ask for it.

Advanced: complete input envelope and optional fields

Edit optional fields using the method dictionary. Apply validates and recalculates the entire input. Unknown values remain null.

Versioned input JSON

Import local JSON or CSV

Files stay in this browser. Maximum 1 MiB. JSON imports are recalculated. CSV supports flat observation tables, with column types taken from the displayed fixture. Empty cells become null.

Workbench JSON / input envelope

CSV target table

CSV file, matching the target table headers

Compare the arrangements

Keep physical resources and evaluation conditions equal. With identical inputs, all three approaches produce identical arithmetic. The comparison refuses material differences in declared conditions; it does not verify those declarations.

Show only differing metric rows

Privacy: comparison inputs may contain sensitive notes or operational details. Storage is off by default. Do not enter personal records or sensitive infrastructure details. Reproduction exports include supplied inputs and notes, including raw small-cell inputs suppressed from CORE-009 result tables. Suppression of displayed results does not make a reproduction export safe to publish.

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Executive brief and reproducible export

Public exercise notes

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Read the generated brief

Method, inputs and limits

Calculate the smallest opening buffer that can meet all declared demand under a schedule of early and late confirmed receipts. Method version 0.2.0. Predict receipts or demand, or size a buffer when expiry, handling capacity, more detailed timing or stock limits matter.

CORE-026 input dictionary
Input	Unit / type	Required interpretation
periods — Ordered receipt and demand schedule	whole stock units per interval / number	Each row has receipts available before demand, demand, and optional lateReceipts available only after demand. Include confirmed, usable receipts only.

Visible mathematics / decision rules

Deficit at demand = previous closing deficit + demand − early receipts.

Minimum opening stock = max(0, largest deficit at demand).

Closing deficit = deficit at demand − late receipts.

What this result cannot establish

A single stock pool, no loss, unrestricted storage, and sufficient delivery capacity.
This is the exact minimum under the supplied timing assumptions. Model a later arrival as late receipts when it cannot meet current demand.

What would falsify the assumptions?

Replay the schedule with the recommended opening stock and confirm each period can meet its demand. One unit less should fail if the minimum is positive.
Assumptions fail if the supplied definitions, units, period, scope or source records are wrong or incomplete.
An independent source audit or replication may contradict an input or the recorded dependency.
This method creates no resources. Physical conservation is checked in the inventory and transfer ledgers; descriptive graphs and checklists are not resource-flow models.
The same equations and review checklist can be reproduced with a spreadsheet or structured human-only process.
This is deterministic arithmetic, a descriptive comparison or a structured governance check, not a fitted causal effect or forecast. Fictional inputs remain an exercise.
Equal or worse measured errors, net review effort, disclosure burden or fallback under MAR would show no added benefit or added risk; no improvement is assumed.

Reproducible fictional fixture and independently calculated expectations

This fixture is synthetic. It does not describe a country, government, company or event.

{
  "observations": {
    "unit": "crates",
    "origin": "synthetic",
    "sources": [
      {
        "id": "SYN-026",
        "kind": "synthetic",
        "label": "Fictional planning exercise",
        "url": null
      }
    ],
    "periods": [
      {
        "receipts": 10,
        "demand": 25
      },
      {
        "receipts": 0,
        "demand": 20
      },
      {
        "receipts": 30,
        "demand": 10
      }
    ]
  },
  "parameters": {}
}

Expected checks

{
  "openingMinimum": 35,
  "finalStock": 20,
  "peakDeficitInterval": 2
}

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Authoritative background references

OECD: OECD Supply Chain Resilience Review: Navigating Risks — Supply continuity and shared dependency context for the fictional planning exercises. Reviewed 2026-11-11. Reference, not endorsement or validation.

These sources inform definitions or review practices. They do not validate this implementation or endorse MAR.

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