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You check Capacity Monitor on Thursday. Your inbound plan for next week just got blocked. Amazon says you are at 98% of your monthly limit, and the two shipments you created yesterday pushed you over. Now you are deciding whether to cancel SKUs, delay the shipment, pay for extra space through Capacity Manager, or move bulk stock to AWD and hope auto-replenishment keeps you in stock.
That scenario plays out every week for FBA sellers. Amazon's capacity limits give you more planning visibility than the old weekly restock system, but they still move faster than most brands can react. If you wait until you hit the limit to figure out your next move, you have already lost margin, missed sales, or both.
This guide explains how Amazon FBA capacity limits work in 2026, what affects them, where to find them in Seller Central, when requesting more space makes sense, and how to manage inventory so limits cause fewer problems.
Amazon FBA capacity limits control how much inventory you can send to and store in Amazon fulfillment centers at any given time. The limit is measured in cubic feet, not units. It includes inventory already at Amazon plus shipments you created but Amazon has not received yet.
Amazon updates your confirmed limit once a month and provides estimated limits for the next two months. Those estimates shift based on your sales velocity, sell-through rate, Inventory Performance Index (IPI) score, storage type, and Amazon's fulfillment center capacity.
The monthly capacity system replaced weekly restock limits in March 2023. The core framework still stands, but sellers report encountering additional constraints that Amazon has not formally announced. Some see ASIN-level restrictions that block replenishment on specific products even when account-wide capacity shows headroom. Others hit days-of-supply limits that prevent sending more than a certain number of weeks' worth of stock for a given SKU. Amazon has not published official guidance on these constraints, but they show up often enough in seller forums and support tickets that operators should plan for them.
Sellers still confuse these terms because Amazon has used all three over the years.
Capacity limits are the current monthly cubic-foot allowances that govern how much you can send to FBA. This is what Capacity Monitor shows.
Restock limits were the old weekly unit-based caps Amazon retired in 2023. Some sellers still use "restock limits" as shorthand for capacity limits, which creates confusion.
Storage limits refer to the maximum on-hand inventory Amazon will accept before charging overage fees. Storage limits and capacity limits overlap, but they are not identical. You can stay within your capacity limit and still get hit with overage charges if your on-hand inventory sits too long without selling.
When sellers say "I hit my limit," they usually mean capacity. When Amazon says "you have excess inventory," they usually mean storage. Knowing which limit you hit helps you pick the right fix.
Amazon's own help documentation uses "capacity," "restock," and "storage" inconsistently. Seller Central shows separate views for Capacity Monitor, FBA Inventory, and Inventory Performance. Each tool frames limits slightly differently. That makes it easy to misdiagnose the problem. If you think you need more capacity when you actually have an inventory health problem, paying for extra space will not help.
Amazon replaced weekly restock limits with monthly capacity limits in March 2023. The change gave sellers more planning time and clearer advance notice. Instead of checking every Monday to see if you could ship that week, you get a confirmed limit for the full month plus estimates for the next two months.
The 2023 rollout also introduced Capacity Manager, which lets sellers request additional space by bidding a reservation fee. Before that, sellers had no formal path to ask for more capacity.
The monthly capacity system reduced short-term uncertainty, but it did not eliminate capacity pressure. Sellers still face limits that change without much warning, especially during Q4 or when IPI scores drop. Amazon still blocks inbound shipments when on-hand inventory or open shipments push usage too high. And the shift from unit-based limits to cubic-foot limits hit sellers of bulky or oversized products harder than they expected.
Starting in 2025, sellers reported encountering new restrictions Amazon has not officially documented. Some saw ASIN-level blocks that prevented replenishment on individual SKUs even when account capacity showed available space. Others hit what appeared to be days-of-supply constraints, where Amazon refused shipments that would push inventory beyond 60 or 90 days of forecasted demand for a specific product.
Amazon has not published help pages explaining these restrictions. Seller support tickets often get vague answers or contradictory guidance. But the reports are consistent enough that operators should assume Amazon may apply additional constraints beyond the account-wide cubic-foot limit.
If you hit a block that Capacity Monitor does not explain, check whether the restriction applies to one ASIN or your whole account. Document what you see, including screenshots and support case numbers. That documentation helps if you need to escalate or decide whether to shift SKUs to FBM.
Amazon calculates your monthly capacity limit based on several inputs. Some you control. Some you do not.
Your Inventory Performance Index (IPI) score is the single biggest lever you control. Amazon measures how efficiently you turn inventory. Scores above 450 generally qualify for higher limits. Scores below 400 put you at risk of lower limits, especially during peak season.
Sell-through rate feeds into IPI. If products sit in FBA for months without selling, your IPI drops and your limit shrinks. Cleaning up aged inventory or slow movers improves sell-through and protects future capacity.
Amazon factors in your recent sales and their internal demand forecasts. If your velocity climbs, your estimated limits often rise. If sales drop, limits tighten.
Seasonal patterns matter. Sellers who ramp for Q4 often see higher limits starting in late summer. Sellers who maintain steady year-round velocity tend to get more stable limits than those with sharp seasonal spikes.
Amazon's forecasts are not always accurate. They do not know about your upcoming promotion or product launch unless sales history signals it. That mismatch can leave you short on capacity right when you need it most.
Your capacity usage includes inventory already at Amazon plus shipments you created but have not been received. If you send a large shipment and it sits in "receiving" status for two weeks, that volume counts against your limit the whole time.
Long lead times between shipment creation and FC delivery can lock up capacity for days or weeks. Tighter shipment cycles reduce that exposure. For more on how receiving timelines affect your planning, see our guide to Amazon FBA processing times.
Amazon allocates capacity by storage type: standard, oversize, apparel, footwear, and in some cases hazmat or flammable. Limits for one storage type do not transfer to another.
Bulky products burn through cubic-foot capacity faster than small, dense items. A seller shipping furniture or large electronics may hit capacity limits long before hitting unit-count expectations. If your average product is oversized, you need tighter forecasting and more aggressive inventory cleanup than a seller moving small, fast-turning items. Learn more about extra-large FBA storage and how it affects capacity.
Your current capacity limit lives in the Capacity Monitor tool inside Seller Central.
Capacity Monitor shows your confirmed limit for the current month, your current usage, and estimated limits for the next two months. Usage includes on-hand inventory plus open shipments. For details on the shipment creation workflow, see our Send to Amazon guide.
Confirmed limit: The cubic-foot allowance for the current month. This number does not change mid-month unless you request and receive additional capacity through Capacity Manager.
Current usage: On-hand inventory plus shipments created but not yet received. If usage approaches 100% of your limit, new shipments may get blocked.
Estimated limits: Projections for the next two months. These can shift week to week based on your sales, IPI, and Amazon's FC capacity.
Available capacity: Confirmed limit minus current usage. This is how much room you have left for new shipments.
If your available capacity drops below what you need for your next planned shipment, you have three options: reduce the shipment size, delay the shipment, or request additional capacity.
Estimated limits are not guarantees. Amazon updates them weekly based on current conditions. A strong estimate this week can drop next week if your IPI falls or if Amazon tightens FC capacity ahead of a major event.
Treat estimates as planning guides, not commitments. If your Q4 plan depends on a high October estimate, have a backup plan in case that estimate drops in September.
Capacity Manager is Amazon's reservation-fee system for requesting additional FBA capacity. It replaced the informal support-ticket process that existed before 2023.
You submit a request specifying how much extra capacity you want (in cubic feet) and the maximum reservation fee you are willing to pay per cubic foot. Amazon reviews all requests each week and grants space starting with the highest fee offers until available capacity runs out.
If your request gets approved, you pay the lowest fee Amazon granted that week, not your maximum bid. That means you can bid high to improve your approval odds without overpaying if demand is soft.
The reservation fee is separate from storage fees. You pay it whether or not you use the extra space.
Amazon offsets your reservation fee with performance credits. You earn $0.15 in credits for every dollar of sales generated using the additional capacity. If your products sell through, credits can offset up to 100% of the reservation fee.
If you request 500 cubic feet at $0.50 per cubic foot, your reservation fee is $250. If you generate $1,667 in sales from that inventory, you earn $250 in credits and pay nothing. If you generate $1,000 in sales, you earn $150 in credits and pay $100 net.
Performance credits only apply to sales from the extra capacity you requested, not your baseline capacity.
Request additional capacity when:
Do not request extra capacity if you are using it to avoid cleaning up aged inventory or if your forecast is uncertain.
Skip Capacity Manager if:
Paying for space you cannot turn productively makes a bad inventory problem more expensive. Fix inventory health first, then request more capacity if your forecast supports it.
Capacity limits create operational friction even when Amazon's intent is reasonable. Here are the problems sellers hit most often.
You create a shipment in Seller Central. Amazon rejects it because current usage plus the new shipment exceeds your confirmed limit. Now you have to decide whether to split the shipment, remove SKUs, delay delivery, or request extra capacity.
This happens most often when:
Prevention: Track open shipments weekly. Do not assume capacity is available just because Capacity Monitor showed room three days ago.
You planned a Prime Day promotion. Your capacity limit is not high enough to support the inventory you need for the event. You request additional space through Capacity Manager, but your bid is not high enough and Amazon denies the request. Now you are choosing between running the promotion with partial inventory or skipping it entirely.
This scenario is common in Q4 when fulfillment center space is tight and Capacity Manager bids run higher than normal.
Prevention: Plan seasonal ramps 90 days out. Request extra capacity early when competition for space is lower. Have a backup plan that includes AWD, 3PL overflow, or FBM fulfillment for part of the catalog.
Amazon blocks a shipment for a specific SKU even though Capacity Monitor shows available space. Seller support says the system flagged the ASIN for exceeding days-of-supply limits, but they cannot explain the exact threshold or how to fix it.
This is frustrating because there is no official help page explaining ASIN-level restrictions. Sellers report thresholds ranging from 60 to 120 days of supply, but Amazon has not confirmed those numbers.
If you hit this, check your sales velocity for that ASIN over the past 30 and 90 days. If you are trying to send six months of stock for a product that sells 10 units a week, Amazon may reject it regardless of account-wide capacity.
You have 200 cubic feet of aged inventory sitting in FBA. It has not sold in 90 days, but you have not removed it because removal fees feel wasteful. That 200 cubic feet counts against your capacity limit and drags down your IPI. Meanwhile, you cannot send enough fast-turning products because your limit is maxed out.
This is one of the most common self-inflicted capacity problems. Sellers hold onto dead stock hoping it will eventually sell, and it costs them the ability to restock winners.
Prevention: Set a hard rule. If a SKU has not sold in 90 days and you have no upcoming promotion planned for it, remove it or liquidate it. The removal fee is cheaper than the opportunity cost of blocked capacity. For step-by-step removal options, see our guide to aging FBA inventory removal.
Capacity limits force tradeoffs. The goal is to make those tradeoffs deliberately instead of reactively. For a broader framework, see our guide to Amazon supply chain management.
The tighter your forecast, the less often you get surprised by blocked shipments or stockouts. Build reorder logic that accounts for:
If your reorder system assumes unlimited capacity, you will keep hitting walls. Build capacity constraints into the forecast so you know weeks in advance when you will run short. For more on this approach, see our overview of common inventory management strategies.
Smaller, more frequent shipments reduce the risk of a single large shipment getting blocked. They also reduce the amount of capacity locked up in "receiving" status.
If you normally send 30 days of inventory in one shipment, split it into two 15-day shipments. That gives you more flexibility to adjust mid-cycle if limits change.
The tradeoff is shipment prep cost. More shipments mean more time creating workflows in Seller Central and more carrier pickups. Weigh that cost against the risk of stockouts or blocked inventory.
Amazon Warehousing and Distribution (AWD) lets you store bulk inventory upstream from FBA. Amazon auto-replenishes FBA based on demand forecasts. AWD inventory does not count against FBA capacity limits.
AWD makes sense when:
AWD does not make sense when:
Do not use AWD just because you are out of FBA capacity. Use it when the economics and lead-time advantages outweigh the added complexity.
If you need overflow storage outside Amazon's network, work with a 3PL that can receive supplier shipments, prep for FBA, and send small batches to Amazon on a schedule. That gives you more control than AWD but requires more hands-on coordination.
Aged inventory costs you twice: once in storage fees, again in lost capacity. If you have products sitting unsold for 90+ days, make a decision.
Options:
All of those options feel like losses. But holding onto dead stock hoping it will eventually move costs more in blocked capacity and dragged IPI than taking the write-off now.
Set a policy. Anything unsold for 120 days gets removed or liquidated, no exceptions. That frees capacity for products that actually turn.
FBA is not the only way to fulfill Amazon orders. Fulfillment by Merchant (FBM) gives you a fallback when FBA capacity runs out.
FBM makes sense for:
FBM requires you to handle pick, pack, and ship. You lose Prime eligibility unless you qualify for Seller Fulfilled Prime. But it keeps products available when FBA capacity would otherwise force a stockout.
Do not treat FBM as the default. Use it strategically for SKUs where FBA capacity cost exceeds the operational cost of self-fulfillment.
Most FBA capacity problems are symptoms of weak inventory planning, not Amazon policy failures. If you keep hitting limits, stockouts, or aged inventory issues, you probably have a systems problem.
If three or more of those apply, you need better planning infrastructure, not just more FBA capacity.
SupplyKick builds inventory planning systems that account for FBA capacity constraints, sales velocity, lead times, and margin targets. We help brands:
If your team is stuck fighting FBA capacity limits every month, we can help you build a system that works with Amazon's constraints instead of against them.
Contact our team to talk about inventory planning support.
Amazon updates your confirmed capacity limit once a month, typically in the third week of each month. Estimated limits for future months update weekly based on your sales, IPI score, and Amazon's fulfillment center capacity. Your confirmed limit for the current month does not change mid-month unless you request and receive additional capacity through Capacity Manager.
Yes, through Capacity Manager. You submit a request specifying how much extra capacity you want and the maximum reservation fee you are willing to pay. Amazon grants requests starting with the highest bids until available space runs out. If approved, you pay the lowest fee granted that week. Performance credits can offset up to 100% of the reservation fee if your products sell through.
You can also increase limits indirectly by improving your IPI score, increasing sell-through, and removing aged inventory.
Yes. Inventory stored in Amazon Warehousing and Distribution (AWD) does not count against FBA capacity limits. Amazon auto-replenishes FBA from AWD based on demand forecasts. That makes AWD useful for staging bulk inventory or seasonal stock without consuming FBA capacity.
AWD has its own fees and requires you to trust Amazon's auto-replenishment logic. It is not a universal solution, but it works well for brands with long supplier lead times or seasonal demand patterns.
Some sellers report that Amazon blocks shipments for specific ASINs when inventory would exceed 60, 90, or 120 days of forecasted demand, even if account-wide capacity shows available space. Amazon has not published official guidance on days-of-supply limits, so the thresholds are unclear.
If you hit this, check your sales velocity for the affected ASIN over the past 30 and 90 days. Reduce the shipment quantity to align with 60-90 days of recent demand, or split the shipment across multiple weeks. Document the block with screenshots and support case numbers in case you need to escalate.
If the restriction persists and the product is slow-moving, fulfill it FBM or hold bulk stock in a 3PL until demand picks up.
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