Amazon IPI Score Optimization: Avoid Storage Limits

TL;DR

• Your Amazon IPI (Inventory Performance Index) is a score from 0 to 1,000 that measures how efficiently you manage FBA inventory, and falling below the threshold of 400 leads to restrictive FBA capacity limits.
• Amazon calculates IPI using four core metrics: excess inventory, sell-through rate, stranded inventory, and in-stock rate.
• The fastest way to recover a low IPI is to remove or liquidate excess and stranded inventory before the quarterly evaluation date.
• FBA capacity limits, measured in cubic feet, restrict how much inventory you can send to FBA, which can cap your revenue ceiling during peak periods like Q4.
• In our experience, sellers who maintain an IPI above 500 year-round almost never face capacity restrictions, even in Q4.
• Proactive IPI management protects your account health and keeps your storage utilization ratio under control.

Amazon IPI score optimization is the process of actively managing your FBA inventory metrics to keep your Inventory Performance Index above Amazon's threshold and avoid restrictive storage limits. A low IPI score is one of the most common and avoidable causes of restricted sending capacity, and it disproportionately hurts sellers during high-demand periods. This guide walks you through exactly how the score works and how to protect it.

Figures in this article reflect Agile Consultancy's internal experience and are not guarantees. Amazon's FBA capacity and IPI rules change over time, so always confirm your current limits and threshold in Seller Central.

What is Amazon IPI Score?

An Amazon IPI (Inventory Performance Index) is an inventory performance metric scored from 0 to 1,000 that Amazon updates regularly to reflect how efficiently you manage your FBA inventory. The score reflects how well you balance in-stock availability against excess and stranded inventory, and Amazon uses it as a key input when setting your FBA capacity limits.

This matters because falling below Amazon's IPI threshold of 400 may lead to more restrictive FBA capacity limits, depending on Amazon's capacity policies. Since March 2023, Amazon manages FBA storage as a single capacity limit measured in cubic feet, shown in the Capacity Monitor in Seller Central and reviewed regularly (typically monthly) based on your IPI, sales history, and available space. For sellers who rely on consistent restocking, a storage limit can cap revenue at the worst possible moment.

How do you optimize your Amazon IPI score?

You optimize your Amazon IPI score by reducing excess and stranded inventory, improving your sell-through rate, and maintaining a strong in-stock rate on your most popular ASINs. Amazon updates the score regularly and uses it, along with your sales history and available capacity, to set the FBA capacity limits shown in your Capacity Monitor.

The most important factors are: excess inventory percentage, 90-day sell-through rate, stranded inventory resolution speed, and in-stock rate on top-selling products. Improving any of these factors can contribute to a higher IPI score, but the biggest gains usually come from clearing excess units that are dragging down your storage utilization ratio.

Key Criteria for Amazon IPI Optimization

• Excess inventory ratio: Keep the percentage of inventory classified as "excess" as low as possible, since it is widely considered one of the most influential factors affecting IPI.
• Sell-through rate: Maintain a healthy 90-day sell-through (units sold divided by average units stored); a higher sell-through rate generally indicates healthier inventory performance.
• Stranded inventory: Resolve any inventory that has lost its active listing quickly, because stranded units count against you and earn zero revenue.
• In-stock rate: Stay in stock on your high-velocity ASINs, as running out of your best sellers signals poor inventory planning to Amazon.
• FBA fees awareness: Track aged inventory surcharges and long-term storage fees, which both signal and worsen excess inventory problems.
• Restock timing: Send inventory in proportion to actual sales velocity rather than overstocking ahead of uncertain demand.

Understanding the Four Pillars of IPI

What it is

The IPI score is built from four core inputs that Amazon weights and combines into a single number. The four pillars are excess inventory, sell-through rate, stranded inventory, and in-stock rate.

Why it matters

Each pillar tells Amazon something different about your operation. Excess inventory shows whether you are tying up fulfillment center space with slow-moving units. Sell-through measures the velocity of your stored stock. Stranded inventory flags units that cannot be sold because of listing issues. In-stock rate shows whether you reliably keep customers' favorite products available.

Impact

In our experience, ignoring even one pillar can cause a sharp IPI drop in a single evaluation. We worked with a kitchenware brand whose score fell sharply in one evaluation because a single high-volume SKU went stranded after a listing suppression, dragging down both the stranded and in-stock metrics simultaneously.

How to optimize

• Audit each pillar separately every two weeks using the Inventory Performance dashboard in Seller Central.
• Treat excess inventory as your top priority since it is the strongest single influence on your score.
• Set automated alerts for stranded inventory so you catch listing issues as quickly as possible.
• Prioritize restocking your top 20% of ASINs that drive 80% of revenue to protect your in-stock rate.

Excess Inventory: The Strongest Influence

What it is

Excess inventory is stock that exceeds the demand Amazon forecasts over a defined period, typically flagged when you hold significantly more than 90 days of supply. It is the most damaging factor in your IPI calculation.

Why it happens

The most common cause of excess inventory is over-forecasting demand and sending too many units ahead of a launch or seasonal event that underperforms. Sellers also accumulate excess when a product's BSR drops and sales velocity falls below the rate at which inventory was planned.

Impact

Excess inventory triggers aged-inventory surcharges, long-term storage fees, and a direct hit to your IPI. One supplements client of ours was paying thousands of dollars a month in storage and surcharge fees on excess units while simultaneously sitting below the IPI threshold, which restricted their capacity and prevented them from sending in their faster-moving SKUs. Strong inventory planning prevents exactly this kind of compounding problem, which is the focus of our Amazon inventory management work.

How to fix

• Run the "Manage Excess Inventory" report weekly and create removal or liquidation orders for the worst offenders.
• Use Amazon's automated pricing or outlet deals to accelerate sell-through on excess units.
• Lower your reorder quantities for any SKU showing more than 90 days of supply.
• Consider Amazon's liquidation program to recover partial value and free up storage utilization fast.

Sell-Through Rate and In-Stock Balance

What it is

Sell-through rate is the ratio of units sold to average units stored over the trailing 90 days, while in-stock rate measures how consistently your top ASINs remain available. Balancing the two is the core challenge of IPI optimization.

Why it matters

These two metrics pull against each other. To improve sell-through you want lean inventory, but to protect your in-stock rate you need enough buffer stock to avoid stockouts. The best approach to balancing them depends on each SKU's sales velocity and lead time.

Impact

Getting the balance wrong costs you in two directions. Too lean and you stock out, losing BSR rank and triggering the in-stock penalty. Too heavy and you accumulate excess, triggering surcharges and the excess penalty. We have seen brands lose a significant share of monthly revenue during a single stockout on a best-selling ASIN, then overcorrect into excess inventory the following quarter.

How to fix

• Calculate days-of-supply per SKU and target 30-60 days for fast movers, less for slow movers.
• Use coverage-based restocking tied to a 30-day rolling sales average rather than fixed reorder dates.
• Split shipments so you send smaller, more frequent replenishments instead of large bulk loads.
• Monitor your in-stock rate weekly and prioritize restocks for ASINs trending toward zero.

Stranded Inventory: The Silent Score Killer

What it is

Stranded inventory is FBA stock that exists in a fulfillment center but has no active, buyable listing attached to it. These units earn nothing and actively damage your IPI.

Why it happens

Stranded inventory typically results from listing suppressions, policy flags, pricing errors that breach Amazon's fair-pricing policy, or accidental listing deletions. Because the units are physically present but commercially invisible, many sellers do not notice until the IPI drops.

Impact

Stranded inventory hits two pillars at once: the stranded metric directly and the in-stock rate indirectly, since a suppressed listing cannot stay in stock. One of our electronics clients had several hundred units stranded for weeks after a compliance flag on a product image, which alone pushed their IPI down sharply before we resolved the listing. From an account health perspective, recurring stranded inventory is also a signal worth monitoring closely, which is why our Amazon brand protection work often overlaps with inventory hygiene.

How to fix

• Check the "Fix Stranded Inventory" page in Seller Central at least twice weekly.
• Set up email alerts for listing suppressions so you act within hours, not days.
• Resolve the root cause (image compliance, pricing, category restriction) rather than just relisting.
• Create removal orders for stranded units that cannot be reinstated to stop them dragging your score.

IPI Optimization Method Comparison

Method	Speed of Impact	Cost	Best Use Case
Remove/dispose excess units	Fast (days)	Removal fees	Aged inventory near long-term storage fees
Liquidation program	Fast (1-2 weeks)	Low recovery value	Bulk excess you cannot sell at margin
Price reduction / outlet deals	Medium (2-4 weeks)	Margin loss	Excess with some remaining demand
Fix stranded listings	Fast (hours-days)	Time only	Suppressed or delisted ASINs
Reduce reorder quantities	Slow (1 quarter)	None	Preventing future excess

How to Optimize Your IPI Score Step by Step

1. Check your current IPI and threshold: Open the Inventory Performance dashboard in Seller Central to see your live score and how far you are from the IPI threshold of 400 that affects your FBA capacity limits.
2. Identify your worst pillar: Compare your four metrics and find which one is dragging the score down most, since this is where your effort returns the highest gain.
3. Clear excess inventory first: Run the Manage Excess Inventory report and create removal, liquidation, or price-reduction actions for the heaviest offenders before the quarter closes.
4. Resolve all stranded inventory: Work the Fix Stranded Inventory page, address the root cause of each suppression, and remove any units that cannot be reinstated.
5. Maintain a healthy in-stock rate: Prioritize replenishment for your top 20% of revenue-driving ASINs so your best-selling ASINs never go to zero.
6. Right-size future reorders: Adjust reorder quantities to a 30-60 day supply target based on rolling sales velocity rather than fixed bulk orders.
7. Set up monitoring cadence: Schedule twice-weekly checks of stranded inventory and weekly checks of excess and in-stock rate so problems never accumulate.
8. Re-evaluate before each quarter close: Audit all four pillars in the final two weeks before Amazon's quarterly IPI snapshot to lock in your improvements.

Common Patterns

Across the brands we manage, the most consistent pattern we see is that excess inventory accounts for the majority of IPI drops, not stockouts. Sellers tend to over-order, especially ahead of Q4, then watch their score sink when demand does not match projections. A second clear pattern is timing: scores improve fastest in the two weeks before the quarterly snapshot when removal and liquidation orders are processed in time. A third pattern is that stranded inventory is almost always overlooked: brands that automate stranded-inventory alerts recover noticeably faster than those who check manually. Finally, brands that keep their IPI above 500 year-round virtually never face restock limits, even during peak season, while those hovering near the threshold get caught off guard every Q4.

Common Amazon IPI Mistakes

• Overstocking before seasonal demand is confirmed
• Ignoring stranded inventory alerts
• Using fixed reorder quantities instead of actual sales velocity
• Letting best-selling ASINs go out of stock
• Waiting until the quarterly evaluation to take action
• Focusing only on sales instead of inventory efficiency
• Treating IPI as a one-time fix rather than an ongoing routine

Frequently Asked Questions

What is a good Amazon IPI score?

A good Amazon IPI score is anything comfortably above Amazon's current threshold. Many sellers aim for 500 or higher to maintain a comfortable margin. Amazon currently sets the IPI threshold at 400, so maintaining a buffer above 500 protects you even if the threshold shifts. In our experience, sellers above 550 rarely face any capacity restrictions, while those near 400 are constantly at risk.

Why is Amazon IPI optimization important?

Amazon IPI optimization is important because a low score leads to restrictive FBA capacity limits that cap how much inventory you can send into fulfillment centers. Those limits directly restrict your revenue ceiling, especially during peak periods like Q4 when you most need inventory. Beyond storage limits, a low IPI usually signals excess inventory bleeding money through surcharges and long-term storage fees, so optimizing the score protects both your capacity and your margins.

How do you raise a low IPI score quickly?

You raise a low IPI score quickly by removing or liquidating excess inventory and resolving all stranded inventory before the quarterly evaluation. These two actions deliver the fastest impact because excess is the biggest contributor and stranded units hurt two pillars at once. In practice, processing removal and liquidation orders in the final two weeks before the snapshot is the highest-leverage move available to a seller in a hurry.

How often does Amazon update the IPI score?

Amazon updates the IPI score continuously, while your FBA capacity limits are reviewed regularly through the Capacity Monitor in Seller Central, based on your IPI, sales history, and available space. Keeping your score above 400 protects your capacity, so we recommend auditing all four pillars regularly rather than scrambling once a quarter, since improvements can move your score up within days.

Conclusion

Amazon IPI score optimization comes down to disciplined inventory management across four pillars: keeping excess inventory low, maintaining a strong sell-through rate, resolving stranded units fast, and protecting your in-stock rate on top sellers. Excess inventory is the strongest single driver and is the most common cause of IPI drops, while stranded inventory is the silent killer that most sellers overlook until it is too late. The single most reliable protection against storage limits is keeping your IPI above 500 year-round so you never get caught off guard during Q4.

Based on our experience managing inventory for Amazon sellers, the sellers who avoid capacity limits entirely are not the ones who react to a low score, but the ones who build a weekly monitoring cadence that prevents the score from dropping in the first place. Treat your IPI as a leading indicator of operational health, not a number to fix once a quarter. A proactive inventory strategy helps reduce the risk of capacity restrictions while maintaining sufficient stock to meet customer demand.