2026-06-09 · 6 min
Amazon Inventory Management: How to Avoid Stockouts and Overstocking
Running out of stock tanks your BSR and ranking. Overstocking ties up capital and incurs storage fees. Here is how to manage inventory on Amazon correctly.
Why Inventory Management Is Critical on Amazon
Amazon ranks products partly based on in-stock history. When you go out of stock, your BSR (Best Sellers Rank) drops quickly and your organic ranking in search results falls with it. Recovering a strong BSR after a stockout can take weeks or months of advertising spend. On the other side, overstocking generates storage fees that compound over time, particularly for large or heavy products and for inventory held longer than 365 days, which incurs the long-term storage fee surcharge.
Using Amazon's Inventory Performance Index
Amazon's Inventory Performance Index (IPI) measures how well you manage inventory across four dimensions: excess inventory, sell-through rate, stranded inventory, and in-stock rate. A score below 400 triggers storage limits and can restrict your ability to send new shipments to FBA. Keep your IPI above 500 by removing excess inventory, fixing stranded listings promptly, and maintaining adequate reorder timing.
Calculating Reorder Points
Reorder point = (average daily sales × lead time in days) + safety stock. Lead time is the time from placing a purchase order to having inventory checked in at an Amazon warehouse. For most suppliers this is 30 to 60 days including production, shipping, and FBA intake. Safety stock is typically 10 to 14 days of average daily sales. If you sell 20 units per day and your lead time is 45 days with 14 days safety stock, your reorder point is (20 × 45) + (20 × 14) = 1,180 units.
Seasonal Demand Adjustment
Static reorder points fail during seasonal spikes. If your product sells 3x as fast in December, your safety stock and reorder point need to scale with the forecast. Review trailing 12-month sales data and adjust reorder calculations before each peak season. Amazon's Sales Dashboard shows week-over-week trends; compare current year to prior year in the same period to identify seasonal patterns.
Tools for Inventory Management
Amazon's native Inventory Planning tool in Seller Central provides replenishment recommendations, though it can be conservative. Third-party tools like RestockPro, SoStocked, and Inventory Lab offer more granular forecasting with supplier-specific lead times, multiple warehouse locations, and custom safety stock rules. For sellers with more than 50 SKUs, a dedicated inventory management tool pays for itself in avoided stockouts and excess storage fees within a few months.