History of Amazon IPI Score: How It Has Evolved

Amazon introduced the Inventory Performance Index (IPI) in 2018 as part of its effort to improve FBA capacity utilization. The initial version had storage limits kick in for sellers scoring below 350. Over subsequent years, Amazon has adjusted the threshold upward several times — it moved to 400, then 450 in some periods, with fluctuations during COVID when demand patterns changed dramatically. During COVID in 2020-2021, Amazon was initially very lenient with storage as e-commerce demand surged. As capacity normalized in 2022-2023, storage restrictions tightened again and Amazon refined the IPI calculation to better reflect modern inventory performance. The formula has also evolved: earlier versions gave more weight to in-stock rate, while recent versions appear to weight sell-through rate and excess inventory more heavily, reflecting Amazon's priority on reducing inventory age and maximizing warehouse throughput. Looking forward, Amazon has consistently moved toward a system where FBA storage is treated as a premium resource that high-performing sellers earn through good inventory management, rather than an unlimited service included in FBA fees.