Amazon Now Uses Best-of-Two Timeframes for IPI Score Calculations
Amazon now calculates the IPI sell‑through metric using both a 90‑day and a 365‑day rolling window and automatically inserts the higher percentage into the IPI formula. The change is live immediately and the IPI threshold of 400 remains unchanged.
Overview
Amazon has updated the way it calculates the Inventory Performance Index (IPI) for Fulfillment by Amazon (FBA) sellers. Starting today, the platform evaluates sell‑through rates over both a 90‑day and a 365‑day rolling window, automatically applying the higher figure to each seller’s score. The change is live for every account and does not require any manual activation.
Key Points
- Dual‑window calculation — Amazon now runs sell‑through metrics for the past 90 days and the past 365 days, then selects the larger value for the IPI.
- Higher score advantage — A seller whose annual velocity is 45 % but whose recent quarter is 30 % will see the 45 % figure used, boosting the overall index.
- No setup needed — The system implements the best‑of‑two logic automatically; sellers do not need to adjust settings or submit requests.
- Immediate effect — The new algorithm is already applied to the IPI displayed in the Inventory Performance Dashboard as of the date of this release.
- Threshold unchanged — The minimum IPI required to avoid storage limits remains at 400 for most sellers, so the change only influences the score, not the benchmark.
- Other IPI components stay the same — Excess inventory percentage, stranded inventory percentage, and in‑stock rate for popular items continue to be weighted as before.
How the New IPI Calculation Works
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Collect sell‑through data — Amazon extracts the number of units sold versus units received for each SKU over the last 90 days and over the last 365 days.
Example: A winter coat line sold 2,000 units in the past year but only 150 units in the most recent quarter. -
Compute two rates — The platform calculates a 90‑day sell‑through rate (150 ÷ 500 = 30 %) and a 365‑day sell‑through rate (2,000 ÷ 4,500 = 44 %).
Example: The same coat line yields a 30 % short‑term rate versus a 44 % annual rate.
Analysis & Recommendations
Why This Matters
By using the higher of the quarterly or annual sell‑through rate, sellers can keep their IPI above the 400 benchmark and avoid storage‑type restrictions that previously resulted from a single slow quarter. The automatic best‑of‑two logic also rewards strong annual performance for seasonal items without extra configuration.
Key Takeaways
- Amazon runs sell‑through calculations for the past 90 days and the past 365 days and selects the larger rate for the IPI.
- The new best‑of‑two logic is applied automatically as of the release date; no manual activation is required.
- The minimum IPI to avoid storage limits stays at 400, so the change only influences the score, not the benchmark.
- Excess inventory, stranded inventory, and in‑stock rate components remain weighted as before.
Recommended Actions
- →Log into Seller Central > Inventory Performance Dashboard to view the updated IPI and compare it with the pre‑change score.
- →Monitor both 90‑day and 365‑day sell‑through percentages in the dashboard and adjust replenishment plans accordingly.
- →Check Seller Central > Inventory > Manage Excess & Stranded Inventory to keep excess inventory below 15% and stranded inventory low.
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