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How working with a 3PL partner can help you avoid Amazon inventory limits?
20 March 2026
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The products you are selling on Amazon are selling well enough that you want to add extra stock, and so you send a new product batch to the Amazon warehouse. And then suddenly you find out that only 1/3 of the shipment was accepted into the warehouse - or worse, Amazon refused to accept the entire shipment. You kept all FBA prep rules perfectly, so where might the problem be?
The answer to this problem might be that you have hit the storage limits on Amazon. Compared to other warehouses, which might let you temporarily use more storage space than usual, Amazon is very strict about how much space each brand can use, and the available space for you can change depending on how quickly the products sell, how much of it sits in storage, and how well it’s managed overall.
But for many sellers, the first sign that something is off is when Amazon blocks or reduces an inbound shipment, as up until that point, everything looks normal — stock is moving, sales are coming in, and there’s no clear signal that you’re running out of space. So while everything feels “under control” on your side, Amazon might already see it differently.
So in this article, we'll look at what actually happens when you exceed your storage limits at Amazon FBA, where this situation usually comes from, how Amazon reacts, and what it might mean for your day-to-day operations.
What are FBA storage limits (and why they exist)
When you start selling with Amazon FBA, it’s easy to assume that storage works like a typical warehouse. You send products in, Amazon stores them, and as long as you’re paying for space, you can keep sending more. But the hard truth is that Amazon doesn’t operate like a traditional storage provider. Every seller is assigned a limited amount of storage space, and that limit is actively managed by Amazon, meaning it can go up or down over time, depending on how your inventory behaves.
At a basic level, there are two types of limits you need to understand:
Storage limits – the total volume your inventory can occupy inside Amazon’s fulfilment centres at any given moment
Restock limits – the maximum amount of new inventory you’re allowed to send in over a specific period
Each of these categories is tracked separately - Amazon looks at how much space your standard-size products take up and how much space your oversize products take up independently.
So for example:
You might still have room to send more small products (like cosmetics or accessories)
but at the same time be unable to send large items (like furniture or bulky equipment), because that specific limit has already been reached
This is often confusing for sellers, because overall stock levels may look fine — but one category is already full, and that’s enough for Amazon to block or reduce part of your shipment.
How Amazon decides how much space you get
This is where things often become less intuitive for sellers. Amazon on a monthly basis evaluates how efficiently you use the space you already have, with the main idea being the faster your inventory sells, the more space you’re likely to get.
To measure that, Amazon looks at several signals:
how quickly your products sell (sell-through rate)
how long units stay in storage
how much of your inventory is actively selling vs sitting idle
whether your listings are available and buyable
how much excess or stranded inventory you have
All of this feeds into your Inventory Performance Index (IPI) — a score Amazon assigns to your account to reflect how well you manage your inventory. In simple terms, IPI answers one question: Are you using Amazon’s warehouse space efficiently, or not?
If your products sell consistently and don’t sit in storage for too long, your score improves. If a large part of your inventory is slow-moving, unsellable, or inactive, your score drops. And that score has a direct impact on how much storage space you’re allowed to use.
Why limits change over time
The most frustrating for sellers part is that because these limits are tied to your inventory performance, they don’t stay the same for long. As your sell-through rate, stock levels, and overall account metrics change, Amazon keeps adjusting how much space you’re allowed to use. Sometimes these changes are gradual. Other times, they become noticeable quite quickly - for example, your next shipment is rejected from entering Amazon's system because your available space was lowered, and so this shipment no longer meets Amazon's requirements.
Seasonality makes this even more visible. Let’s say in November and December you sell 1,000 units per month, so sending in a large shipment makes sense — most of it moves quickly. But in January, demand drops and you’re suddenly selling 300 units instead. That same stock now sits in the warehouse much longer. From Amazon’s point of view, your inventory has become slower-moving and takes up space for longer periods. As a result, the amount of storage you’re allowed to use can be reduced.
At the same time, Amazon updates how it evaluates your inventory on a regular basis. If more of your stock starts sitting unsold, your performance score drops. And when that happens, you may notice that you can send fewer units in your next shipment or that your restock limits are reduced - until your score improves again.
Why Amazon introduced storage limits in the first place
But why would Amazon invent such strict inventory limits? That's actually pretty simple - from Amazon’s perspective, the goal is to keep inventory moving. Their fulfilment centres are designed for high turnover, not long-term storage and slow-moving products take up space that could be used for items that sell quickly.
So instead of offering unlimited storage (and dealing with overcrowded warehouses), Amazon:
prioritises fast-selling inventory
limits space for slower-moving stock
pushes sellers to manage inventory more actively
The longer products sit in storage, the more space they occupy without generating turnover. As more of your inventory behaves this way, Amazon begins to limit how much additional stock you can send — even if you still feel like you’re operating at a reasonable level. So the issue isn’t just how much stock you have, but how long it takes to sell through it. This is why sellers often run into storage limits without noticing it early. The numbers may look fine on your side, but from Amazon’s perspective, the inventory is simply moving too slowly.
When do sellers exceed their storage limits
In most cases, you don’t suddenly “cross a limit” out of nowhere.
What usually happens is much more practical: you keep sending more inventory based on how your business is performing at the moment, but one slower period and at some point, the total amount of stock in Amazon simply grows faster than your sales can absorb. You might be restocking regularly, increasing order sizes, or preparing for higher demand - but Amazon only sees that more and more units stay in storage longer than expected and that’s when you start getting close to your limit.
Accidentally getting close to the limit or exceeding it is especially common in the situations below:
1. Sending larger shipments than your actual sales can support
First scenario is probably the most common one. Expecting a higher demand for your products and wanting to avoid running out of stock, you send enough to cover the next 2–3 months, rather than just a few weeks.
For example:
you sell around 10 units per day (≈300/month)
you send 1,200 units in one shipment
However, if the higher demand doesn't come and you sold only 300 units this month, that means 900 units are still sitting in storage and slowly becoming aged stock. After another month meanwhile, a large part of your inventory is sitting in Amazon’s warehouses for 60–90 days or longer. And that has two direct consequences. First, your sell-through rate drops, because you’re holding much more stock than you’re actually selling within a given period. Second, that inventory continues to count fully toward your storage usage for weeks or months.
As a result, when you try to send your next shipment, you may notice that Amazon reduces the number of units you’re allowed to send, your restock limit is lower than before or that, worse case scenario part of your shipment is rejected, because according to Amazon, you are already using too much warehouse space.
2. Continuing to restock at the same level despite slowing sales
Another very common situation is when you base your replenishment on past performance, rather than adjusting the restocking to current sales. Let's say that for a while, your product sells around 400 units per month, so you keep sending similar quantities to stay in stock. After a while though, the sales drop to around 250 units per month. You don’t immediately adjust your shipments, since you think the slower period will end soon and the demand will recover, so you continue sending roughly the same amount as before.
Over time, two things start happening:
your total inventory in FBA keeps increasing
your sell-through rate drops, because a larger share of your stock remains unsold
From Amazon’s perspective, this means you’re using more warehouse space without generating proportional sales. And that’s exactly what affects your limits. When your sell-through drops and inventory stays longer in storage, Amazon adjusts how much additional stock you’re allowed to send. So when you create your next shipment, you may notice that the maximum quantity you can send is lower than before, as a direct result of inventory building up faster than it’s being sold.
3. Replenishing low-selling products at the same level as bestsellers
Another common mistake is to treat a poorly selling product the same one as bestselling one, less selling one when planning shipments and ordering the same amount of both. For example, let's say that Product A sells 15 units per day and Product B sells 1 unit every 2–3 days. Despite the visible sales difference, you shipped 300 of both products to Amazon. And while Product A starts clearing almost immediately, product B, on the other hand, barely moves. After a few weeks, most of that stock is still sitting in storage.
If you keep replenishing both products in the same way, the slower one starts building up:
more units remain unsold after each cycle
older stock is still there when new stock arrives
Eventually, a growing part of your storage is taken up by products that generate very little sales and from Amazon’s perspective, this lowers the overall efficiency of your inventory as a larger share of your stock is sitting in the warehouse instead of moving through it. That shift affects your sell-through rate and, as a result, reduces how much additional inventory you’re allowed to send — even if your bestsellers are performing well.
4. Sending new shipments before earlier stock has sold down
This usually comes from how shipments are timed, not from sending unusually large quantities. You plan inventory ahead, based on production and shipping timelines, so the next batch is already on the way before the previous one has had time to sell through. For example, you send 1,000 units at the beginning of the month. After a few weeks, around half of that stock is still in Amazon’s warehouse but at the same time, your next 1,000 units arrive.
Instead of reducing your stock level, you’ve just increased it. Now you’re not selling through one batch of inventory, but working through overlapping shipments. Your total stock jumps up, and at your current sales pace, it will take significantly longer to clear. That longer storage time is what changes how Amazon evaluates your inventory as more units are sitting in the warehouse at the same time, and each of them is expected to stay there longer before being sold. If this pattern repeats over a few cycles, your average inventory level keeps growing — and that’s when Amazon starts limiting how much additional stock you can send.
What happens when you exceed your FBA storage limits
It might happen that you won't realise you’ve hit your limit until you try to send your next shipment. You prepare your inbound plan, enter the quantities into the system and then Amazon immediately reduces them. In some cases, you might find out that you can’t send anything at all! And then unfortunately you’re no longer deciding freely how much stock to send - instead, Amazon is deciding how many items you can send to their warehouse and when. And those limits don’t just affect your shipments - they start influencing how you restock, how your products perform, and how stable your sales are as well.
1. Your inbound shipments are partially accepted instead of fully approved
When you create a shipment, Amazon doesn’t necessarily reject it outright. Much more often, it quietly changes it.
You might prepare a shipment of 1,000 units, based on your current sales and what you know you’ll need over the next few weeks. But once you enter that into the system, Amazon reduces the quantity — for example, to 600 units. The rest simply can’t be included because it's over the storage limit for your store.
At that point, your plan stops matching reality. Those remaining 400 do stay with you — at your supplier, in your warehouse, or already prepared for shipping — but with no immediate way to send them to FBA. This forces you to adjust on the spot and, for example, you might need to either delay part of the shipment, split it into smaller batches, or start rethinking which products to prioritise. And that’s where the problem becomes operational, as instead of sending inventory based on how quickly products sell, you start making decisions based on what Amazon currently allows.
2. You lose control over how quickly you can restock your bestsellers
Let’s say you have a SKU that sells around 20 units per day. Based on that, you plan to send enough stock to cover the next few weeks, so you don’t risk running out. But when you create the shipment, Amazon limits how much you can send and you’re only able to send a smaller quantity. Because you sent fewer units than planned, your stock starts running down faster than expected and soon the product goes out of stock because you weren’t able to replenish it properly.
At that point, even if you’re ready to send more units, you may still be close to your storage limit so you can’t immediately correct the situation.
This creates a gap where:
the product is out of stock
demand is still there
but you can’t restock fast enough to meet it
And while this is happening, the inventory that caused the limitation is still sitting in the warehouse. Slower products continue to occupy space, but they don’t generate enough sales to free it up, so unless you take a part of the poor-selling stock from Amazon and free the storage space, you can't send more of your bestselling products to meet the demand - that’s what makes this situation difficult.
3. A growing part of your stock stops contributing to sales
Saying that not all products behave the same way might sound like something obvious, but the difference between your bestsellers and slow-moving stock is becoming especially visible when you are dealing with warehouse space shortage. Some SKUs sell consistently and free up space as units leave the warehouse. Others move much more slowly, which means they stay in storage for weeks or months. They don’t sell fast enough to clear space, so they remain in the warehouse while new shipments keep arriving and as a result, your total inventory keeps growing — even if your actual sales don’t.
Because those units are still counted as part of your inventory, they reduce the amount of space available for new shipments so when you try to send more stock, Amazon may limit how much you can add, simply because too much of your existing inventory is still sitting in storage.If this pattern continues, your total stock can reach or exceed the level Amazon allows for your account - and that’s when restrictions and additional costs can start to apply.
4. Your storage costs increase without improving your revenue
If your total inventory goes beyond the storage limit assigned to your account, Amazon doesn’t just block new shipments — it can also start charging storage overage fees. These fees are calculated based on how much you exceed your limit and how long your inventory stays above that threshold.
For example, if your storage limit is set at a certain volume and your inventory goes over it, the excess portion is charged separately from standard storage fees. The longer your stock remains above that limit, the higher the total cost becomes.
What makes this particularly problematic is that these fees are usually driven by inventory that is already moving slowly, so you end up in a situation where:
the products that caused the overage are not selling fast enough
they remain in storage for longer
and they continue generating additional fees over time
In other words, you’re paying extra for inventory that is already underperforming — and the longer it stays in that state, the more it costs you.
5. You may need to remove inventory earlier than planned
At some point, reducing your stock inside FBA becomes the only way to regain control. You might have inventory that could still sell over time, but keeping it in Amazon’s warehouse is no longer practical as it occupies space that you need for other products, and it limits your ability to send new shipments. Then the only option left might be removing part of that inventory, meaning selecting specific SKUs that are not selling fast enough and creating removal orders to get them out of Amazon’s warehouses. Those units are then sent back to your own storage, even though they are still sellable, because you’re choosing between:
keeping a few hundred slow-moving units in FBA for the next 2–3 months
or freeing up that space now so you can send in products that sell every day
And in that situation, removing inventory becomes the only way to regain control over what you can actually sell when you have a tightly limited warehouse space.
6. Your sales performance becomes less stable
Over time, all of these changes start to affect how your business performs on a day-to-day basis. Some products run out of stock earlier than expected because you couldn’t replenish them in time - and when your bestseller goes out of stock, the effect shows up almost immediately.
Let’s say your product was selling consistently every day and appearing high in search results. Once it becomes unavailable, customers can no longer buy it — so Amazon starts showing alternative products instead. After a few days, your listing stops generating sales entirely. And because sales velocity is one of the key factors Amazon uses to rank products, your position in search results begins to drop.
Others products meanwhile remain in storage for long periods without selling. For example, a product that you expected to sell within a few weeks may still have most of its stock sitting in the warehouse after a month or two. Only a small number of units leave storage each week, so the majority of that inventory stays in place. During that time, those units continue to take up space in FBA every single day. They don’t free up room for new shipments, and they don’t generate enough sales to offset the space they occupy.
So not only you aren't earning as much as you could from your bestselling products, you are losing money on slow-moving products - double the loss.
What to keep in mind
If you look at all of these situations together, one thing becomes clear. Storage limits are not something you suddenly “hit” by accident. In most cases, you get there step by step. You send a bit more stock to stay safe. A few products start selling more slowly. One shipment arrives before the previous one has fully sold, etc. And over time, more units stay in the warehouse than leave it. That's when Amazon reminds you that warehouse space is a tightly limited resource and restricts your future shipments while charging you for the extra space you used. At this point, it's Amazon deciding how much stock you can send to their warehouses and sell, not you.
But there's a way to turn the situation around.
In the next article, we’ll look at what you can do in those situations — how to free up space, how to avoid getting blocked on shipments, and how to keep your inventory at a level that actually supports your sales instead of limiting them.
