Amazon FBA Inventory Management: Avoid Fees and Stock Smarter

You send 2,000 units to FBA in January. Sales are steady through March — 12 units a day, margins look healthy. Then in July you check your payments report and find $1,400 in aged inventory surcharges on a single ASIN. The product was profitable. The inventory management was not.

I have been on both sides of this mistake. I have paid storage fees that ate an entire quarter’s profit on a SKU, and I have also run out of stock at the worst possible time — mid-PPC ramp — and watched my organic rank evaporate in 72 hours. Both hurt. But only one of them is completely preventable with a spreadsheet and a calendar.

Most Amazon sellers fall into one of two traps: they overstock because they are afraid of going out of stock, or they understock because they are afraid of storage fees. The result is the same — money lost, either to Amazon’s warehouses or to competitors who took your ranking while you waited for your next shipment.

This article breaks down how FBA storage fees actually work in 2026, what the Inventory Performance Index (IPI) score means for your storage limits, how to calculate your restock timing with a simple formula, and six tactics to keep your inventory lean without burning cash.

Key Takeaways

Monthly storage fees range from $0.78 to $2.40 per cubic foot depending on season and size tier. Aged inventory surcharges start at 181 days and escalate sharply after 365 days.

Your IPI score determines how much space Amazon gives you. Below 400, you get storage limits that can block your next shipment.

Restock timing is a math problem: (daily sales velocity × lead time) + safety stock = reorder point. Get this right and you solve 80% of inventory headaches.

Create removal orders or use FBA Liquidations before the 181-day surcharge window. A $0.25 removal fee beats a $6.90 per-cubic-foot surcharge.

Keep FBM listings active as backup. When your FBA inventory hits zero, FBM keeps the listing alive and the ranking intact.

How Amazon FBA storage fees work in 2026

Amazon charges two types of storage fees, and confusing them is how sellers get blindsided.

Monthly inventory storage fees are charged per cubic foot for every unit sitting in a fulfillment center. The rates depend on size tier and time of year:

Standard-size (January–September): $0.78 per cubic foot
Standard-size (October–December): $2.40 per cubic foot
Oversize (January–September): $0.56 per cubic foot
Oversize (October–December): $1.40 per cubic foot

These fees are assessed on the 15th of each month based on your average daily volume for that month. Q4 rates are roughly three times higher than the rest of the year — which means inventory that sits through October, November, and December costs you triple, regardless of whether it sells during the holiday rush.

Aged inventory surcharges are the real margin killer. Amazon applies additional charges based on how long units have been in the warehouse:

181–270 days: $1.50 per cubic foot
271–365 days: $3.80 per cubic foot
365+ days: $6.90 per cubic foot or $0.15 per unit, whichever is greater

That last tier is brutal. A standard-size product taking up 0.5 cubic feet costs you $3.45 in aged inventory surcharge per unit after one year — on top of the monthly storage fee. If your unit cost is $5 and you sell for $20, that surcharge just wiped out a huge chunk of your margin on every unit that has been sitting too long.

The surcharge is assessed on the 15th of each month using a first-in, first-out (FIFO) calculation. Amazon tracks the age of every unit from the date it arrives at the fulfillment center, not the date you created the shipment. You can verify the current rates on Amazon’s FBA fee schedule and run product-level estimates with the Revenue Calculator.

Pro tip: Check your Aged Inventory report in Seller Central weekly — go to Inventory → Inventory Planning → Manage Excess Inventory. The “estimated aged inventory surcharge” column tells you exactly what you will owe if you do not act. See my breakdown of FBA fee-saving tactics for more ways to keep these costs down.

What is the IPI score and why it matters

The Inventory Performance Index (IPI) is Amazon’s scorecard for how well you manage your FBA inventory. It is a number between 0 and 1,000, and it directly controls how much storage space Amazon allocates to your account.

Amazon calculates IPI using four factors:

Sell-through rate: How quickly your inventory sells relative to how much you send in. Higher velocity = higher score.
Excess inventory percentage: Units Amazon considers overstocked based on your sales history. More excess = lower score.
Stranded inventory percentage: Listings that have FBA inventory but no active offer. Even one stranded ASIN drags your score down.
In-stock rate: How often your popular, well-selling ASINs stay in stock. Going out of stock on a top seller hurts this metric.

Amazon does not publish the exact weighting, but from my experience, sell-through rate and excess inventory have the biggest impact. Fixing stranded inventory gives you the fastest improvement because it goes from “dragging you down” to “not a factor” overnight.

The threshold that matters: If your IPI drops below 400, Amazon imposes storage volume limits on your account. That means you literally cannot send in more inventory until you either sell through what you have or remove it. During peak season, a storage limit can kill your Q4. The threshold has shifted in the past — it was 450 at one point — so check the current number in Seller Central under Inventory → Inventory Dashboard.

You can see your IPI score in Seller Central at Inventory → Inventory Dashboard. It updates weekly. If you are between 400 and 500, treat it as a warning. Above 550 is comfortable. Above 700 means you are managing inventory well. Amazon’s IPI FAQ page explains the scoring details and current thresholds.

How to calculate your restock timing

Restock timing is not a gut feeling. It is a formula:

Reorder Point = (Average Daily Sales × Lead Time in Days) + Safety Stock

Lead time is the total number of days from when you place the order with your supplier to when the inventory is checked in and available at Amazon. This includes manufacturing time, shipping, customs, prep, and Amazon’s receiving window. For a product sourced from China with sea freight, a realistic total lead time is 45–60 days. For domestic suppliers, it might be 14–21 days.

Safety stock is your buffer against demand spikes or shipping delays. A common rule is 14 days of average sales, but adjust based on your supply chain reliability.

Here is a real example. Say you sell a product at an average of 10 units per day with a 30-day lead time (domestic supplier):

Reorder Point = (10 units/day × 30 days) + (10 units/day × 14 days safety stock)
Reorder Point = 300 + 140 = 440 units

When your FBA inventory hits 440 units, you place your next order. By the time the new shipment arrives and is checked in 30 days later, you will have roughly 140 units left — your safety stock. If a demand spike happens or your supplier ships late, that two-week buffer keeps you in stock.

For products sourced from China with a 60-day lead time, the same calculation looks like this:

Reorder Point = (10 × 60) + (10 × 14) = 600 + 140 = 740 units

That is a much larger reorder point, which means more capital tied up in inventory. This is where understanding your true COGS matters — you need to know exactly what each unit costs you to sit in a warehouse so you can decide whether the capital cost of a larger safety stock outweighs the risk of a stockout.

Pro tip: Track your daily sales velocity per ASIN in a spreadsheet, not just the 30-day average in Seller Central. Seller Central’s averages smooth over spikes and dips. A product that sells 15 units a day in week one and five units a day in week four has a 10-unit average, but your restock timing needs to account for the trend, not just the mean.

6 tactics to manage inventory without burning cash

1. Use Amazon’s restock recommendations — but verify them

Seller Central provides restock recommendations under Inventory → Inventory Planning → Restock Inventory. These suggestions are based on your sales velocity, lead time settings, and current stock levels. They are a decent starting point.

But do not follow them blindly. Amazon’s algorithm does not know about your upcoming promotions, seasonal demand shifts, or supplier constraints. I have seen the tool recommend 3,000 units for a product I was planning to discontinue. Use the recommendations as one data point, not the final answer.

Set your lead time correctly in the restock tool settings. If it defaults to seven days and your actual lead time is 45 days, the recommendations will be dangerously wrong.

2. Set up restock alerts

Amazon allows you to configure alerts in the restock tool that notify you when inventory drops below a certain threshold. Set these to trigger at your calculated reorder point — not at “low stock,” which is often too late.

You can also use third-party tools like SoStocked or Inventory Lab for more granular alert logic, including accounting for multiple purchase orders in transit. But for most sellers with fewer than 20 SKUs, the built-in alerts plus a simple spreadsheet work fine.

3. Create removal orders before aged inventory surcharge kicks in

If a product is approaching the 181-day mark and sales are not going to clear the remaining units, create a removal order. Amazon charges $0.25–$0.50 per unit to remove standard-size items and $0.60–$1.00 for oversize. Compare that to the $1.50 per cubic foot surcharge starting at 181 days, and the math is clear.

Set a calendar reminder for every SKU at the 150-day mark. That gives you 30 days to either run a promotion to sell through the remaining units or initiate a removal order before the surcharge hits. You can have units returned to you, donate them, or use the disposal option if the product has no resale value.

4. Use FBA Liquidations for slow movers

Amazon’s FBA Liquidations program lets you sell excess inventory to liquidation buyers at a discounted price. You recover some value — typically 5–10% of the selling price — which is better than paying storage surcharges on inventory that is not moving.

To access it, go to Inventory → Manage Excess Inventory and look for the “Create Liquidations Order” option. The payout is small, but it clears the inventory from your account, stops the fee clock, and frees up storage capacity for products that actually sell.

5. Diversify with FBM for backup

Keep a Fulfilled by Merchant (FBM) offer active on your top-selling ASINs. When your FBA inventory runs out, the FBM listing kicks in automatically. You ship from your own stock — or a 3PL — at a higher handling cost, but the listing stays alive.

This matters more than most sellers realize. A listing that goes out of stock for even five to seven days can drop 20–30 positions in organic ranking. Recovering that rank through PPC can cost far more than the margin you lose fulfilling a few orders yourself. When I plan a first product launch, I always factor in FBM as an insurance policy for exactly this scenario.

6. Build a seasonal planning calendar

Q4 is where inventory management either makes or breaks your year. Amazon’s send-in deadlines for Black Friday and Cyber Monday inventory typically fall in early October. If you miss those deadlines, your inventory is stuck in transit while your competitors sell.

Build a calendar that maps backward from key selling dates:

September 1: Finalize Q4 demand forecast based on prior year data and current velocity.
September 15: Place Q4 orders with suppliers.
October 1–7: Create FBA shipments and ship to Amazon. This is the last comfortable window for inventory to be checked in before peak season.
November 1: Verify all Q4 inventory is received and active. If not, activate FBM backup.

Outside of Q4, watch for category-specific spikes. Outdoor products peak in spring. Back-to-school supplies ramp in July. Tax-season-related products sell in January through April. Your FBA startup cost planning should account for the cash flow cycle these seasonal swings create.

The stranded inventory problem

Stranded inventory is FBA stock that sits in Amazon’s warehouse with no active listing attached to it. The units exist, they are taking up space, you are paying storage fees on them — but customers cannot buy them because there is no live offer.

Common causes of stranded inventory:

Listing suppressed by Amazon for missing information, compliance flags, or restricted keywords.
ASIN deactivated because of an IP complaint or a category change.
Pricing error that triggered Amazon’s fair pricing policy and deactivated the offer.
Listing deleted accidentally — it happens more than you would think, especially with bulk edits.
Brand Registry issues where another seller’s claim conflicts with yours.

The fix is straightforward but requires regular monitoring. Go to Inventory → Fix Stranded Inventory in Seller Central. Amazon shows you every stranded ASIN and the reason it is stranded. Most issues can be resolved by updating the listing, submitting an appeal, or re-listing the product.

The cost of ignoring stranded inventory goes beyond storage fees. Every stranded ASIN drags your IPI score down, which can eventually trigger storage limits on your entire account. I check for stranded inventory every Monday morning — it takes two minutes and prevents problems that take weeks to fix.

Pro tip: After any bulk listing edit or flat file upload, check the stranded inventory report within 24 hours. Flat file errors are the number-one cause of accidentally stranded inventory, and catching them early means you lose one day of sales instead of two weeks.

What to do this week

Inventory management is not a one-time setup. It is a weekly discipline. But you can start with two actions today:

Check your IPI score. Go to Inventory → Inventory Dashboard in Seller Central. If you are below 500, review your excess and stranded inventory immediately.
Pull your Aged Inventory report. Sort by “days in warehouse” descending. Any SKU past 150 days needs a decision: run a promotion, create a removal order, or liquidate. Do not let it cross 181 days without a plan.

Inventory is not the glamorous part of running an Amazon business. Nobody makes YouTube videos titled “I checked my aged inventory report and it was exciting.” But the sellers who track these numbers weekly are the ones who keep their margins intact while everyone else wonders where the money went.

For more on keeping your FBA costs under control, check out my guide to saving money on FBA fees. And if you want to see how all these costs fit into your overall unit economics, the $0.50 mistake breakdown shows you the full fee stack most sellers miss.

I share more inventory management walkthroughs and real seller mistakes on my YouTube channel — subscribe to @AmazonFBAGirl for weekly breakdowns that skip the hype and focus on the numbers.