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24 December 2025How Amazon Decides Where to Store Your Inventory
24 December 2025
OUR GOAL
To provide an A-to-Z e-commerce logistics solution that would complete Amazon fulfillment network in the European Union.
Fulfillment Center Performance Metrics Explained
Why Amazon Tracks Fulfillment Center Performance Metrics
Amazon uses metrics to optimize its massive network—ensuring fast delivery, efficient space use, and low costs. For FBA sellers, these metrics directly impact storage limits, fees, restock ability, and even account health.
In 2026, with AI-driven oversight (Project Amelia), thresholds are stricter. Low scores = restricted storage, higher fees, or suspension risk.
Master these metrics to keep unlimited inventory access and minimize costs.
Inventory Performance Index (IPI): The Master Score
What It Is
IPI (0–1000) measures how efficiently you manage inventory across Amazon FCs.
Components:
- Excess inventory
- Sell-through rate
- In-stock rate
- Stranded inventory
2026 Thresholds
- ≥500: Unlimited storage + no overage fees
- 450–499: Reduced limits
- <450: Strict limits + quarterly reviews
Impact: Low IPI → can’t send new stock → sales drop.
How to Improve
- Sell-through: Target 8–12% weekly
- Fix stranded listings weekly
- Remove excess quarterly
Order Defect Rate (ODR): Customer Satisfaction Score
What It Is
% of orders with defects (negative feedback, A-to-z claims, chargebacks).
Threshold: <1% (target <0.7% for safety)
Impact
1%: Account deactivation risk
- High ODR hurts Buy Box and search rank
Common Causes
- Poor packaging → damage
- Wrong item shipped
- Late delivery (your prep issues)
How to Improve
- Quality control + inspections
- Branded, protective packaging
- Respond to claims fast
Late Shipment Rate (LSR) and Valid Tracking Rate (VTR)
Late Shipment Rate
% of orders shipped after promised date.
Threshold: <4%
Valid Tracking Rate
% of orders with valid carrier tracking.
Threshold: >95%
Impact: Violations → account health drop, possible deactivation.
How to Improve
- Ship same/next day after order
- Use Amazon Buy Shipping or partnered carriers
- Buffer handling time in listings
Cancellation Rate
% of orders you cancel (pre-shipment).
Threshold: <2.5% (<1% ideal)
Impact: High rate → deactivation risk.
How to Improve
- Accurate forecasting
- Buffer stock for demand spikes
- Pause listings if low stock
In-Stock Rate and Restock Limits
% of time your listings are in stock.
Impact: Low rate lowers IPI and sales rank.
Restock Limits: Based on IPI + velocity → caps how much you can send.
How to Improve
- Forecast 60–90 days ahead
- Use Amazon’s Restock Inventory tool
- Maintain 30–45 days supply
Storage Utilization and Excess Inventory
Storage Utilization
How efficiently your inventory sells relative to space used.
Excess Inventory %
90 days supply → flagged
- Penalizes IPI heavily
2026 Fees
- Aged >270 days: $6.90/cu ft
- Excess surcharge on high %
How to Improve
- Liquidate/remove slow-movers
- Run promotions on overstock
- Target 4–6 inventory turns/year
Other Key Metrics
| Metric | Threshold | Impact | Improvement Tip |
|---|---|---|---|
| Customer Service Dissatisfaction Rate | <1% | Account health | Respond <24h, proactive refunds |
| On-Time Delivery Rate (FBM) | >97% | Prime eligibility (SFP) | Reliable carriers |
| Return Dissatisfaction Rate | Low as possible | Feedback + claims | Accurate listings, quality checks |
| Unit Session Percentage | Higher better | Search rank | Optimized listings + images |
How Amazon Uses These Metrics Overall
- Account Health Rating: Composite score
- Performance Notifications: Warnings before deactivation
- IPI Drives Everything: Storage, fees, growth potential
Low metrics → vicious cycle: less stock → fewer sales → lower IPI.
Proven Tactics to Boost Performance 2026
- Weekly Dashboard Review Check IPI, ODR, stranded in Seller Central.
- Automated Alerts Tools like Sellerboard or Helium 10 notify low stock/excess.
- Quarterly Clean-Up Remove/liquidate stranded + aged inventory.
- Demand Forecasting Use Amazon Forecast + historical data.
- Quality Focus Inspections + protective packaging → lower defects/returns.
Brands maintaining IPI >650 average 30–50% higher growth.
Conclusion
Fulfillment center performance metrics aren’t arbitrary—they measure how well you partner with Amazon’s network.
Hit thresholds (IPI ≥500, ODR <1%, LSR <4%) → unlimited growth, lower fees, Prime speed. Fall below → restrictions, higher costs, stalled sales.
Treat metrics like KPIs: monitor weekly, fix issues fast.
Log into Seller Central today—check your IPI and top 3 problem areas. One month of focused improvement can unlock unlimited storage and accelerate your 2026 growth.
Master the metrics—and Amazon’s fulfillment power works for you.
Need a logistics partner who understands the importance of getting every detail right? Contact FLEX..
