2026-06-30 · 6 min read
Amazon FBA Inventory Management in 2026: What You Need to Track
How to manage Amazon FBA inventory in 2026: key metrics (Days of Supply, IPI Score, Sell-Through Rate), avoiding stockouts and excess fees, and when to use third-party tools.
## What Is Amazon FBA Inventory Management?
FBA (Fulfilled by Amazon) inventory management means controlling how much stock you send to Amazon's fulfillment centers, when you replenish, and how you avoid the two main failure modes: stockouts (losing the Buy Box and ranking) and excess inventory (storage fees, long-term storage fees, and capital tied up in slow-moving stock).
## The Core Metrics to Watch
Days of Supply: how many days your current inventory will last at your current sales rate. Target: 30-60 days of supply in FBA for most products (adjust for lead times). Sell-Through Rate: units sold divided by average inventory held over a period -- Amazon uses this to assess storage efficiency. IPI Score (Inventory Performance Index): Amazon's composite score (0-1000); below 400 triggers storage limits. Aim for 450+.
## Avoiding Stockouts
Set reorder points based on your lead time plus a safety buffer. For a product with a 30-day manufacturing lead time and 14-day shipping lead time, you need to reorder when you have at least 44 days of supply remaining (plus a buffer). Use Amazon's Restock Inventory tool as a starting point, but validate with your own sales velocity data -- Amazon's tool uses trailing 30-day velocity and may not account for upcoming promotions or seasonality.
## Avoiding Excess Inventory
Long-term storage fees apply to units in FBA for more than 365 days. Monthly storage fees vary by size tier and season (October-December rates are higher). If a product is moving slowly: consider a lightning deal or coupon to accelerate sell-through, or create a removal order to bring stock back for repackaging or liquidation via other channels.
## Replenishment Tools
Amazon's native Restock Inventory tool is free and adequate for sellers with under 50 SKUs. Third-party tools (Inventory Lab, SoStocked, RestockPro) offer more granular controls, multi-supplier management, and better handling of seasonality. For sellers with 100+ SKUs and complex replenishment cycles, these tools pay for themselves quickly.