Amazon FBA Inventory & Restock Management

Published 17 September 2026 · SellersOS Inventory & Supply Chain Capability Guide

SellersOS provides high-precision Amazon FBA inventory planning, automated reorder forecasting, and supply chain telemetry designed for Amazon brand owners, multi-account operators, and aggregators. By integrating directly with official Amazon Selling Partner APIs (SP-API) using Non-Restricted operational roles, SellersOS eliminates costly stockouts, prevents overstock storage surcharges, and audits FBA fee discrepancies.

1. FBA restock forecasting & Days of Supply (DOS)

Stockouts severely harm Amazon organic search rank, Buy Box share, and advertising efficiency. SellersOS computes continuous sell-through run rates across multiple trailing windows (7-day, 14-day, 30-day, 60-day, and 90-day velocity) with outlier damping for temporary stockouts or promotional spikes.

Metric & Analysis	Operational Value	Data Source
Days of Supply (DOS)	Dynamic calculation: Current FBA Available + Reserved + Inbound divided by normalized daily sales velocity. Color-coded health indicators flag urgent restock alerts.	SP-API FBA Inventory Summaries
Reorder Quantity (ROQ)	Calculates exact units required based on target buffer stock, factory lead time, ocean/air transit time, and Amazon FBA check-in latency.	Configured supplier lead times & SP-API sales velocity
Stockout Run-Rate Projection	Forecasts the exact calendar date when current inventory will hit zero if no purchase order or inbound shipment is initiated.	Real-time inventory ledger telemetry

2. Supplier lead-time & buffer stock modeling

Modern Amazon supply chains require granular segmentation between production cycles, freight forwarder transit, customs clearance, and Amazon FBA warehouse receiving delays.

• Configurable Lead-Time Pipelines: Set individual lead times per supplier, SKU, and marketplace, accounting for manufacturing days and port-to-warehouse transit.
• Safety Stock & Seasonal Buffers: Configure dynamic buffer stocks for peak retail events (Prime Day, Q4 Holiday Season, Spring Sale) to ensure high-demand ASINs remain fully stocked.
• Multi-Warehouse Visibility: Track inventory across Amazon FBA fulfillment centers, third-party logistics (3PL) prep facilities, and inbound container shipments in a single pane of glass.

3. Inbound logistics & shipment tracking

SellersOS tracks the full lifecycle of FBA inbound shipments from purchase order generation through Amazon warehouse check-in:

• Shipment Status Telemetry: Real-time tracking of Working, Shipped, In-Transit, Delivered, Checked-In, and Closed FBA shipments.
• Receiving Discrepancy Detection: Automatically compares units shipped against units received by Amazon fulfillment centers to detect lost boxes or miscounted cartons.
• Inbound Placement Fee Awareness: Visibility into Amazon FBA inbound placement service options and split-shipment configurations to optimize inbound shipping costs.

4. FBA fee & dimensional weight auditing

Amazon fulfillment fees and storage charges are calculated based on item packaging dimensions and unit weights. Packaging changes or scanner measurement errors can quietly reduce unit profitability over thousands of orders.

Audit Module	Inspection Criteria	Resolution Output
FBA Fulfillment Fee Audit	Compares current charged fee against catalog dimensions and weight tiers to identify overcharges.	Flagged SKU report for Amazon remeasurement requests
Aged Inventory Surcharge	Identifies units exceeding 180 and 365 days in FBA facilities before high surcharges accrue.	Liquidation, discount, or removal recommendations
Inventory Reconciliation	Cross-references warehouse lost, damaged, and customer returned units against Amazon reimbursements.	Audit ledger of unreimbursed inventory claims

5. Data protection & SP-API architecture

SellersOS is engineered strictly around Amazon's security principles:

• Official Amazon SP-API Integration: Connects securely using OAuth 2.0 Login with Amazon (LWA) authorization. SellersOS never asks for or stores Seller Central login credentials.
• Zero Buyer PII Storage: All inventory and restock calculations operate exclusively on non-PII operational data (SKUs, ASINs, quantities, order item counts, fee breakdowns). Customer personal data is not requested or persisted.
• Enterprise Data Security: Data in transit is protected using TLS 1.2 or higher (TLS 1.3 preferred). Data at rest is encrypted using AES-256 via AWS KMS. Logical tenant isolation ensures complete database separation between selling partners.

6. Supported Amazon marketplaces

SellersOS supports all major Amazon regional marketplaces across North America, Europe, and Asia-Pacific:

• North America: United States (Amazon.com), Canada (Amazon.ca), Mexico (Amazon.com.mx).
• Europe: United Kingdom (Amazon.co.uk), Germany (Amazon.de), France (Amazon.fr), Italy (Amazon.it), Spain (Amazon.es), Netherlands (Amazon.nl).
• Asia-Pacific: Japan (Amazon.co.jp), Australia (Amazon.com.au).