Amazon IPI Score Explained: What It Is, Why It Drops, and How to Fix It

The Number That Controls Your FBA Access

Your IPI score is Amazon's judgment of how well you manage their warehouse space. Let it drop below the threshold and your storage limits shrink, your fees climb, and your in-stock rates take the hit, cascading into ranking drops that are hard to reverse.

The Inventory Performance Index (IPI) is a 0-1000 score Amazon assigns to every FBA seller. It reflects how efficiently you use FBA storage relative to your sales velocity. You can find it under Inventory > Inventory Performance in Seller Central.

This guide covers exactly how Amazon calculates your IPI score, the most common reasons it drops, and a prioritized action plan to recover it - organized by how fast each fix will move the needle.

What Is the Amazon IPI Score?

The Inventory Performance Index measures how efficiently you use FBA storage capacity. Scores range from 0 to 1000. A higher score reflects better inventory health, faster sell-through, and fewer stranded or excess units sitting in Amazon's fulfillment centers.

Amazon updates your IPI score weekly, based on a rolling 90-day performance window. That rolling average matters - short-term improvements take time to fully register, and short-term damage takes time to fully clear.

The current threshold that triggers storage restrictions is a score below 400, though Amazon can and does adjust this. Always verify the current threshold directly in Seller Central, as it is subject to change based on platform policy updates.

Amazon created the IPI system because FBA capacity is finite. Every cubic foot of shelf space occupied by slow-moving inventory is unavailable to higher-velocity sellers. The IPI score incentivizes efficient inventory management - and restricts access for sellers who treat FBA as a long-term warehouse.

How Amazon Calculates Your IPI Score

Amazon uses four weighted factors to calculate your IPI score. Two carry the heaviest influence: excess inventory percentage and sell-through rate. Together they represent the majority of your score. Amazon does not publish the exact formula - the weighting is proprietary, similar to the Buy Box algorithm.

Excess Inventory Percentage

This measures what percentage of your FBA inventory is considered excess - meaning you have more units on hand than Amazon's demand forecasting suggests you need for the next 90 days. Excess inventory drives up storage costs and signals poor ordering discipline.

Sell-Through Rate

Sell-through rate tracks how quickly your inventory sells relative to what you have in stock. Amazon calculates it as units sold and shipped over the past 90 days divided by the average number of units on hand during that same period. A low sell-through rate signals that your inventory is not moving efficiently.

Stranded Inventory Percentage

Stranded inventory refers to FBA units that are physically in Amazon's warehouse but are not attached to an active, buyable listing. These units cannot sell, yet they still occupy storage space and accumulate fees. Even a small amount of stranded inventory signals account management problems.

In-Stock Rate for Replenishable Items

This factor tracks how consistently you keep replenishable ASINs in stock. It applies specifically to products Amazon identifies as regularly purchased items - not all ASINs are flagged as replenishable.

One important distinction: Amazon has confirmed that IPI points are not directly deducted for running out of stock. The in-stock rate is a dashboard metric that influences your score, but stockouts themselves do not automatically penalize your IPI. This is one of the most common misconceptions sellers carry into their IPI recovery strategy.

A single bloated ASIN can drag down your entire account score. If you have 50 healthy ASINs and one product with 8 months of excess inventory sitting in FBA, that one product inflates your excess inventory percentage and suppresses your account-level sell-through rate - affecting your overall IPI regardless of how well the rest of your catalog performs.

Why IPI Scores Drop: The Most Common Causes

Most IPI problems trace back to a reactive approach to inventory management. Here are the patterns that cause the most damage.

Overordering Before Q4

The most common IPI killer: brands order aggressively heading into peak season, Q4 ends, and slow-moving units sit in FBA through Q1 and Q2. What feels like prudent preparation becomes dead weight that takes months to clear.

Seasonal Products Left in FBA Past Their Window

Seasonal and trend-driven products need hard sell-by dates baked into your removal strategy. A Halloween product still sitting in FBA in January is excess inventory actively suppressing your IPI score - and accruing storage fees in the process.

Stranded Listings

Listing suppressions, category issues, pricing errors, and compliance flags can all strand inventory. When a listing goes inactive and you do not catch it immediately, units accumulate fees without generating any sales, and your stranded inventory percentage climbs.

Failed New Product Launches

A new ASIN that does not gain traction creates a compounding problem. It generates poor sell-through data while simultaneously adding to your excess inventory percentage. The longer you leave it in FBA without intervention, the more damage it causes.

Bundling and Variation Issues

Incorrect bundle configurations or variation relationships can create ghost inventory - units that appear in FBA but cannot be sold as listed. These situations are often invisible until you audit your stranded inventory report.

How to Fix a Low IPI Score: Prioritized Action Plan

Not all IPI fixes are equal. Prioritize the actions that move your score fastest, then build toward structural improvements that prevent the problem from recurring.

Immediate Actions: 0-30 Days

Fix stranded inventory first. This is the fastest win available. Go to Inventory > Fix Stranded Inventory in Seller Central and work through every ASIN on the list. Many strandeds are simple listing fixes, a price error, a missing attribute, that take minutes to resolve. Others require removal orders.

Create removal or disposal orders for genuinely dead SKUs. If an ASIN has not sold in 90 days and you have no promotional plan to move it, the storage costs and IPI damage are not worth the carrying cost. Disposal is often the better financial decision.

Run lightning deals or coupons to accelerate sell-through on excess stock. Reducing your price or increasing visibility to clear excess units improves two IPI factors simultaneously - excess inventory percentage and sell-through rate.

Medium-Term Actions: 30-90 Days

Recalibrate your reorder quantities using 90-day sell-through data, not historical units-per-week habits. Many sellers over-order because they optimize for never stocking out without running the actual storage cost math on the downside.

Shift some FBA inventory to FBM for slower-moving SKUs. Fulfilling a product yourself temporarily while you clear FBA stock reduces your storage footprint and improves your IPI without requiring a removal order.

Use Amazon's restock recommendations as a calibration tool, not as gospel. Their suggestions are useful directionally but do not account for your specific margin thresholds, promotional plans, or seasonal patterns.

Structural Fixes

Build 90-day sell-through targets into your ordering process before you place purchase orders. If a product cannot realistically sell through within 90 days at current velocity, you are ordering too much.

Establish a monthly IPI review as a standing part of your account management rhythm. Waiting until your score drops below 400 to act means you are already in damage control mode. Monitoring IPI monthly lets you catch declining sell-through or creeping stranded inventory before it becomes a crisis.

What Happens When Your IPI Falls Below the Threshold

When your IPI score drops below Amazon's threshold (currently 400, subject to change), Amazon imposes storage capacity restrictions by storage type - standard-size, oversize, apparel, footwear, aerosol, and flammable. Each storage type can receive independent restrictions.

As of 2025, enforcement is immediate. Sellers falling below the threshold now face capacity restrictions right away, rather than waiting for a quarterly review cycle. Amazon also applies excess inventory fees and storage utilization surcharges when limits are exceeded - the specific fee structures are subject to change, so verify current rates in Seller Central.

The compounding effect is what makes a low IPI score genuinely dangerous. Reduced inventory capacity leads to stockouts. Stockouts cause ranking drops on high-velocity keywords. Ranking drops reduce organic sales velocity. Lower sales velocity makes your IPI harder to recover, because the sell-through rate continues to fall. Breaking this cycle requires immediate intervention, not gradual course correction.

What Elite Brands Do Differently

The brands that consistently maintain strong IPI scores treat it as a leading indicator, not a lagging one. They do not wait for their score to drop to 410 before reviewing inventory health.

• Weekly stranded inventory audits are non-negotiable. Stranded inventory compounds quickly, and the fix is almost always simple when caught early.
  

• Promotional calendars are built around inventory aging, not just revenue targets. When a product hits 60 days of excess stock, a promotion is already planned - proactive, not reactive.
  

• Sell-through is modeled before placing purchase orders. The question to ask before ordering: how much can we realistically sell through FBA in 90 days at current velocity?
  

• FBM is treated as a strategic overflow valve, not a fallback channel. Shifting inventory between FBA and FBM based on sell-through projections keeps IPI scores stable during slow periods.
  

Frequently Asked Questions

What is the Amazon IPI score and why does it matter?

The Inventory Performance Index (IPI) is a 0-1000 score Amazon assigns to FBA sellers that reflects how efficiently you use their warehouse space. It matters because scores below the threshold trigger storage capacity restrictions, excess inventory fees, and limits on sending new shipments - all of which can compound into stockouts and ranking drops.

What is the minimum IPI score to avoid storage restrictions?

The current threshold is a score below 400, though Amazon adjusts this threshold based on fulfillment center capacity and platform policy. Always verify the current requirement in Seller Central under Inventory > Inventory Performance, as relying on a cached figure can lead to unexpected restrictions.

What are the four factors that make up my IPI score?

Amazon calculates IPI using excess inventory percentage, sell-through rate, stranded inventory percentage, and in-stock rate for replenishable items. Excess inventory and sell-through rate carry the most weight. Amazon does not publish the exact formula - the calculation is proprietary.

How long does it take for IPI to recover after I fix inventory issues?

IPI uses a rolling 90-day window, so meaningful recovery typically takes 4-12 weeks after you take corrective action, depending on the severity of the issue and how quickly the underlying metrics move. Fixing stranded inventory produces the fastest visible improvement because stranded units can be resolved immediately. Sell-through rate improvement takes longer to average into the score.

What is stranded inventory and how do I fix it?

Stranded inventory is FBA stock that is physically in Amazon's warehouse but not associated with an active, buyable listing. It can happen due to listing suppressions, pricing errors, compliance flags, or catalog issues. Fix it by going to Inventory > Fix Stranded Inventory in Seller Central and working through each flagged ASIN - either resolving the listing issue or creating a removal order.

Can one bad ASIN affect my entire IPI score?

Yes. IPI is calculated at the account level. A single product with months of excess inventory in FBA will inflate your overall excess inventory percentage and suppress your account-level sell-through rate, even if the rest of your catalog is performing well.

Should I use removals or liquidations to improve IPI?

Both are valid depending on the product. Removals return inventory to you and make sense for products you can still sell through other channels. Liquidations sell inventory to Amazon's liquidation partners at a fraction of cost and are more appropriate for products with no remaining channel value. For IPI purposes, both reduce your storage footprint and improve your excess inventory percentage - the financial trade-off is the deciding factor.

How does IPI score affect my ability to send FBA shipments?

When your IPI falls below Amazon's threshold, Amazon assigns storage capacity restrictions by storage type (standard-size, oversize, apparel, footwear, aerosol, flammable). If you are at or near those limits, you cannot send new inbound shipments for affected storage types until you create capacity - either by selling through existing inventory or creating removal orders. As of 2025, restrictions apply immediately when the threshold is crossed, rather than at a quarterly review.

How Amazon Growth Lab's Account Management Service Protects Your IPI Score

A low IPI score signals that your inventory management process is reactive rather than proactive. Most sellers get into IPI trouble the same way: overordering, missing stranded inventory, and failing to model sell-through before placing purchase orders.

The structural fix is building sell-through modeling, stranded inventory review, and IPI monitoring into your standard account management cadence - so you catch problems when they are small rather than when they have already triggered storage restrictions.

Amazon Growth Lab's full account management service includes exactly this: weekly stranded inventory reviews, inventory forecasting built around 90-day sell-through targets, and monthly IPI monitoring as part of every client's account health protocol. 

If your IPI score is already in trouble, or you want to ensure it stays healthy, we can run a full inventory audit and build a recovery plan specific to your catalog.

Get a free Amazon account audit from Amazon Growth Lab.