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 ^[1] 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

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