---
title: FBA Inventory Management System — Four-Stage Pipeline
type: article
created: '2026-04-05'
updated: '2026-04-05'
source_docs:
- raw/2026-02-11-weekly-call-w-gilbert-121611520.md
tags:
- amazon
- fba
- inventory
- operations
- awd
- stockouts
layer: 2
client_source: null
industry_context: null
transferable: true
---

# FBA Inventory Management System — Four-Stage Pipeline

## Overview

FBA inventory must be tracked through four discrete stages from the moment it is planned for shipment until it becomes sellable stock. Collapsing these stages into a single "in-stock" view — or spreading them across multiple spreadsheets — creates blind spots that cause stockouts. The canonical system described here uses a single spreadsheet, shipment ID reconciliation, and a months-of-inventory velocity metric to ensure zero FBA stockouts.

This system was formalized in response to recurring stockout failures on the [[clients/solarize/index|Solarize]] account, where inventory in transit from the farm was invisible to the team and sales dropped as a result.

---

## The Four Stages

Every unit of inventory must be assigned to exactly one of the following stages at all times:

| Stage | Definition |
|---|---|
| **1. Planned to Ship** | Shipments being prepared by the warehouse/ops team. Inventory is packaged and ready but has not yet left the facility. |
| **2. Shipped — Not Received** | Inventory that has left the farm/warehouse and is in transit, but has not yet been acknowledged by Amazon. |
| **3. Receiving** | Amazon has acknowledged the shipment and is processing it, but units are not yet in sellable stock. |
| **4. In-Stock** | Sellable inventory available at FBA. |

Inventory moves sequentially through these stages. It is never invisible — if it has left the warehouse, it must appear in Stage 2 until Amazon confirms it, at which point it moves to Stage 3, then Stage 4.

---

## Key Metrics

### Months of Inventory

The primary health metric for each SKU:

```
Months of Inventory = FBA In-Stock Units ÷ Monthly Velocity
```

- **Threshold:** When months of inventory falls below **3 months**, replenishment activity must be triggered immediately (i.e., a new Stage 1 planned shipment).
- **Planned Months of Inventory** extends this view to include all pipeline stages:

```
Planned Months = (In-Stock + Planned + Shipped + Receiving) ÷ Monthly Velocity
```

This gives a forward-looking picture of coverage and prevents reactive scrambling.

---

## Shipment ID Reconciliation

Every shipment must be assigned a **Shipment ID** and tracked individually through all stages.

- When a shipment is created (Stage 1), log the Shipment ID, SKUs, quantities, and planned ship date.
- When it leaves the facility (Stage 2), record the actual ship date.
- When Amazon acknowledges it (Stage 3), confirm the Shipment ID appears in Seller Central and verify quantities match.
- When it moves to sellable stock (Stage 4), the Shipment ID can be retired from active tracking.

**If a Shipment ID does not appear in Amazon within a reasonable window after the ship date, open a case with Amazon immediately.** Shipments can be lost in transit; without ID-level tracking, losses go undetected indefinitely.

> "It's like money going to your bank. You know that somebody sent you money, and you're waiting for it to arrive. You don't forget about it." — Mark Hope

---

## Single-Spreadsheet Requirement

All four stages must be visible in **one spreadsheet**, not distributed across multiple tabs, tools, or team members' heads. The spreadsheet should include:

- Farm inventory: bulk (unpackaged) and packaged (ready-to-ship)
- One row or section per SKU, with columns for each pipeline stage
- Shipment ID column linked to active in-transit and receiving shipments
- Monthly velocity input per SKU
- Calculated months-of-inventory (current) and planned months-of-inventory
- Visual or conditional alert when months of inventory drops below threshold

---

## Operating Principle

Zero FBA stockouts is a non-negotiable standard. A zero in the FBA in-stock column is a team failure, not a system failure. The pipeline system exists to make stockouts structurally impossible: if months of inventory is monitored continuously and replenishment is triggered at the threshold, inventory never reaches zero.

> "Our job is for there never to be a zero in the FBA column. Never. Ever. Ever." — Mark Hope

---

## Related

- [[clients/solarize/index|Solarize Client Overview]]
- [[clients/solarize/meetings/2026-02-11-fba-inventory-tracking-overhaul|Meeting: FBA Inventory Tracking Overhaul (2026-02-11)]]