📦 Restock Limits Explained: IPI Score and FBA Capacity

Amazon's Inventory Performance Index (IPI) Score and FBA Capacity Limits are two interconnected systems that directly control how much inventory you can store and send to Amazon's fulfillment centers. For FBA sellers, these limits can quietly throttle your ability to restock fast-moving products — costing you sales, rank, and revenue. In this guide, you'll learn how both systems work, how they interact, and the practical steps you can take to protect and expand your storage capacity.

The IPI Score is a metric Amazon uses to evaluate how efficiently you manage your FBA inventory. It's a rolling score, typically ranging from 0 to 1,000, calculated based on four key factors:

Amazon historically uses a threshold of 400 as the minimum IPI Score to avoid storage restrictions. Scores above 400 give you access to standard or higher capacity. Scores below this threshold can trigger reduced storage limits and added scrutiny.

FBA Capacity Limits are monthly caps (measured in cubic feet) that determine the maximum volume of inventory Amazon will allow you to store across its fulfillment network. These limits are assigned at the account level — not per ASIN — and are updated on a rolling monthly basis, typically announced three weeks before the start of each month.

As of Amazon's current system, capacity is broken down by storage type:

Each category has its own limit, so a seller with high oversize volume and low standard-size volume will see very different constraints than a seller running a mixed catalog.

Your IPI Score influences your capacity allocation. Sellers with higher IPI Scores are generally rewarded with larger capacity limits because Amazon trusts they'll turn inventory efficiently. Sellers with lower scores may receive tighter limits, making it harder to send in enough stock — which can ironically cause stockouts that further hurt IPI.

Understanding this feedback loop is critical: poor inventory management leads to a lower IPI, which leads to tighter capacity, which leads to stockouts, which leads to lower in-stock rate, which further depresses IPI.

Monthly storage fees are charged per cubic foot for inventory stored at Amazon fulfillment centers. These fees increase significantly in Q4 (October–December). Additionally, aged inventory surcharges (formerly long-term storage fees) apply to units stored beyond 181 days and again at 271+ days. Excess inventory sitting in your storage allocation doesn't just cost you money — it also drags down your IPI Score.

Amazon has shifted over the years between restock limits (controls on how much you can ship in) and storage limits (controls on how much you can hold). The current system primarily uses capacity limits, which govern the maximum inventory you can have stored at any given time. When you hit your limit, your shipments will be rejected or require you to remove existing inventory before sending more in.

Start by understanding where you stand right now.

💡 Pro Tip: Amazon announces your next month's capacity limits approximately three weeks before the month begins. Mark this date on your calendar each month so you can plan shipments proactively rather than reactively.

Stranded inventory is one of the fastest ways to hurt your IPI Score because it takes up space without generating any sales. It happens when your FBA units have no active, buyable listing — caused by listing errors, price alerts, or suppressed offers.

💡 Pro Tip: Set a weekly calendar reminder to audit stranded inventory. Amazon can strand listings due to policy changes, pricing violations, or category restrictions — often with little notice to the seller.

Excess inventory drags down both your IPI Score and your cash flow. Amazon flags inventory as excess when you have more than 90 days of supply on hand relative to your sales velocity.

💡 Pro Tip: Use Amazon's Recommended Removal report (found in Inventory Planning) to get a pre-calculated list of units Amazon recommends you remove. This is a fast way to identify the highest-impact removals without manual analysis.

Your sell-through rate measures units sold and shipped over the last 90 days divided by the average number of units on hand. A higher sell-through rate tells Amazon your inventory moves efficiently.

Your in-stock rate component of IPI focuses on your highest-velocity, highest-revenue products. Amazon wants to see these items consistently available.

💡 Pro Tip: Stockouts on your best sellers hurt IPI and organic ranking simultaneously. A single prolonged stockout can take weeks of advertising spend to recover from. Prioritize in-stock health on your top 20% of revenue-generating ASINs above everything else.

Instead of sending inventory in large, infrequent bulk shipments, shift to a more frequent, demand-aligned replenishment model.

This rolling model keeps your days of supply in the optimal IPI range, reduces excess inventory risk, and ensures you never have more than 90 days sitting static in a fulfillment center.

💡 Pro Tip: During Q4, compress this model to a 20/45/60 day cycle. Amazon fulfillment centers get congested, receiving times slow down, and you want a tighter feedback loop to avoid both stockouts and excess inventory accumulation.

Amazon allows sellers to request additional capacity beyond their assigned limit. This is a formal request process within Seller Central.

💡 Pro Tip: Submit capacity increase requests at least 4–6 weeks before your anticipated peak demand period. Waiting until you're already constrained leaves you no runway to restock in time if the request is delayed or requires follow-up.

Fulfilled by Merchant (FBM) listings allow you to sell products directly from your own warehouse or a third-party logistics provider (3PL), bypassing FBA capacity limits entirely. This is a strategic tool — not just a fallback.

IPI is a rolling metric, not a snapshot. Consistent weekly monitoring prevents small issues from compounding into score-damaging problems.

💡 Pro Tip: Your IPI Score updates weekly, but the impact on your next month's capacity is calculated using a snapshot taken at a specific point in the month. Confirm the exact evaluation date in your Seller Central dashboard so you know the deadline for making IPI improvements that will affect your upcoming capacity allocation.

Seller profile: New FBA seller, 6 months in, selling private label home goods.
​ The problem: During their first Q4, they sent in a large bulk shipment to capitalize on holiday demand. They hit their FBA capacity limit and Amazon began rejecting inbound shipments on their fastest-selling SKU. They had excess stock on slower SKUs but couldn't get their winners into Amazon in time.
​ The action taken: They submitted a removal order for 3 months of slow-moving inventory, freeing up cubic feet. They also submitted a capacity increase request 3 weeks before peak demand and created FBM backup listings for their top two ASINs.
​ The result: They recovered 600+ cubic feet of capacity, kept their top ASINs in stock through Black Friday, and finished Q4 with a 94% in-stock rate on their top products. Their IPI Score improved from 390 to 467 within six weeks.

Seller profile: Established FBA seller with a 200+ ASIN catalog across standard-size and oversize categories.
​ The problem: Their IPI Score was hovering around 420 — above the threshold but low enough that their capacity limits were restricting growth. Their oversize category was nearly full, but most of the space was occupied by 8 slow-moving oversize SKUs representing less than 5% of total revenue.
​ The action taken: They conducted an ASIN-level profitability audit. They discontinued 5 of the 8 underperforming oversize SKUs, submitted removal orders, and reallocated that capacity to their top-performing standard-size products. They also ran a targeted PPC campaign to clear the remaining slow-moving oversize units.
​ The result: IPI Score climbed from 423 to 611 over 60 days. Their overall capacity allocation increased by 28% in the following month's assignment, giving them the room to scale their best-performing product lines heading into a new season.

Seller profile: Mid-size seller with 50 ASINs, primarily in apparel.
​ The problem: A batch of 12 ASINs became stranded after a category policy change that triggered price alerts on their account. They didn't notice for 6 weeks. During that time, stranded inventory made up 18% of their total FBA units, causing their IPI Score to drop from 510 to 348 — below Amazon's threshold.
​ The action taken: They audited stranded inventory immediately, fixed the pricing issue on 9 ASINs, and submitted removal orders for the remaining 3 (which were outdated variations). They also set up a weekly stranded inventory review process.
​ The result: IPI recovered to 430 within 8 weeks. Their capacity limits, which had been reduced during the low-IPI period, were restored to normal levels the following month. The total cost of the error — in storage fees, removal fees, and lost sales from restricted capacity — was estimated at over $3,400.

Why sellers do it: The instinct is to over-stock to prevent running out, especially before a promotion or peak season.

Why it backfires: Sending more than 90 days of supply inflates your excess inventory percentage, directly dragging down your IPI Score. It also increases your storage fee exposure and ties up cash in slow-moving units.

What to do instead: Use a demand forecast based on your last 30–90 days of actual sales data. Send 45–60 days of supply per shipment, then replenish based on actual velocity — not worst-case assumptions.

Why sellers do it: Most sellers don't review their Capacity Monitor until they receive a shipment rejection or a warning notification.

Why it backfires: By the time you're at capacity, you've already lost the runway to restock fast-moving products. Capacity increase requests take time, and there's no guarantee of approval.

What to do instead: Review your Capacity Monitor weekly as part of your standard inventory workflow. Submit increase requests 4–6 weeks before any anticipated demand spike — not after it has started.

Why sellers do it: It's easier to apply blanket restock rules across an entire catalog than to manage each ASIN individually.

Why it backfires: Slow-moving ASINs consume limited capacity that could be occupied by your highest-revenue, highest-margin products. You end up protecting low-performing inventory at the expense of your best sellers.

What to do instead: Tier your catalog by revenue contribution and sell-through velocity. Prioritize FBA capacity for your top 20% of revenue-generating ASINs. Move slow movers to FBM or reduce their FBA quantities to free space for products that earn it.

Why sellers do it: IPI feels like an abstract metric until it causes a real consequence like reduced capacity.

Why it backfires: IPI is a lagging indicator. By the time your score drops below 400, the underlying problems — stranded inventory, excess stock, poor sell-through — have already been compounding for weeks. The capacity impact follows shortly after.

What to do instead: Set a personal performance target of maintaining an IPI Score above 500, not just above 400. This buffer gives you room to absorb seasonal fluctuations and supply chain disruptions without ever falling into the restricted zone.

Why sellers do it: Sellers plan their restocks assuming Amazon will receive and process inventory within 2–5 business days as advertised.

Why it backfires: During peak periods (especially Q4), Amazon receiving can slow to 7–21 days or more. If you're reordering with tight lead times, your inventory can be "in transit" and not yet available for sale right when demand peaks.

What to do instead: During Q4 and major sale events (Prime Day, Black Friday), add a 14-day buffer to your normal receiving time assumption. Ship earlier than you think you need to, and monitor your shipment status in Seller Central closely.

When you actively manage your IPI Score and FBA capacity using the strategies in this guide, here's what you can expect:

Amazon updates your IPI Score on a weekly basis. However, the specific snapshot date that Amazon uses to determine your next month's capacity limits is announced within your Seller Central Capacity Monitor. It's important to know this date because actions you take after the snapshot will not affect your upcoming month's allocation — they'll influence the month after that.

If your IPI Score falls below Amazon's minimum threshold (historically 400), Amazon may reduce your FBA storage limits below the standard allocation. This means tighter capacity limits that restrict how much inventory you can hold. You won't be suspended or banned from FBA, but your ability to restock fast-moving products may be significantly curtailed until your score recovers. The best response is immediate action on stranded inventory and excess stock.

It's possible to request a capacity increase regardless of your IPI Score, but your approval odds are meaningfully lower when your score is below Amazon's preferred range. Amazon evaluates capacity increase requests holistically, weighing your IPI, recent sales velocity, and account history. A seller with a score of 350 is unlikely to receive a large capacity increase. The most reliable path to sustained higher capacity is improving the underlying IPI sub-metrics.

Yes, indirectly. Smaller, more frequent shipments help because they reduce the risk of accumulating excess inventory (more than 90 days of supply). They also make it easier to respond quickly to changes in demand velocity. However, the direct IPI benefit comes from the outcome — lower excess inventory percentage and better sell-through rate — not from the act of shipping more frequently itself. You'll also want to weigh the trade-off of higher inbound shipping costs with smaller, more frequent sends.

Capacity limits and IPI Scores are marketplace-specific. Your IPI Score and capacity on Amazon.com (US) are separate from your metrics on Amazon.co.uk, Amazon.de, or other international marketplaces. If you sell across multiple Amazon marketplaces, you need to monitor inventory performance independently in each Seller Central account. Strategies for improvement are the same across marketplaces, but the numbers and thresholds may differ.