Amazon FBA Inventory Management Guide

Inventory directly drives ranking, cash flow, fee exposure, and your ability to scale. Stockouts cost ranking that takes weeks of ad spend to win back; overstock freezes cash and triggers aged-inventory surcharges. For a physical-products seller, inventory management largely is the business.

Lead time = supplier production + transit + customs + Amazon check-in. Typical overseas private-label lead times run 45–90 days. Always plan for the realistic worst case, not the average — a supplier who normally ships in 25 days might take 40 in peak season.

Start with daily sales velocity from a recent representative window (7/30/90 days). Adjust for trend (growing or shrinking), seasonality, and planned promotions or ad pushes. Practical formula: Forecast = Base Velocity × Period Days × Trend Factor × Seasonal Factor. Refine monthly.

Lead Time Demand = Avg Daily Sales × Lead Time. Safety Stock buffers variability: simple method = Avg Daily Sales × 14–30 buffer days; variability method = (Max Daily Sales × Max Lead Time) − (Avg × Avg). Reorder Point = Lead Time Demand + Safety Stock — reorder the moment sellable + inbound stock drops to that level.

Order Quantity = Avg Daily Sales × Target Days of Supply. Most sellers target 60–120 days per order. Faster-growing sellers order smaller and more often to stay flexible; established sellers order larger batches to capture volume discounts when holding cost permits.

Q4 storage rates (Oct–Dec) are roughly 3× the rest of the year. Aged-inventory surcharges start at 181 days. Plan arrivals to sell through quickly rather than sit through the expensive months — and remove or liquidate dead stock before it crosses 365 days.