How do I manage FBA stock alongside my other channels?

What FBA inventory management involves

When you use FBA, Amazon owns the warehouse, the counting and the shipping. You own the stock, the cost of storing it, and the job of sending the right amount at the right time. Amazon's guide to inventory management lists the same basic loop for any seller: receive stock, store it, fulfill orders, and replenish. With FBA, the middle two steps happen in Amazon's buildings, and you watch them through Seller Central, the dashboard where you run your Amazon business.

So the work is four things: know what you have, know what it costs to keep, know what you are allowed to send, and catch what goes wrong. Each is covered below. For the general version of this job across any warehouse, see my inventory management system guide.

What FBA inventory costs

Amazon lists two basic FBA costs: fulfillment, charged per unit sold by size and weight, and storage, charged monthly on the space your stock fills. Storage is calculated from your daily average volume in cubic feet.

Cost	What Amazon shows (as of November 2026)
Storage, standard-size, January to September	$0.78 per cubic foot per month
Storage, standard-size, October to December	$2.40 per cubic foot per month
AWD bulk storage (see below)	$0.48 per cubic foot per month
Aged inventory charge	Charged monthly on items stored for more than 181 days
Returns processing, removals, inbound placement	Separate charges, listed on Amazon's pricing pages
Professional selling plan	$39.99 a month plus selling fees

Those storage rates come from Amazon's supply chain page, and oversize items, low-inventory and storage-utilization fees follow other schedules. Amazon changes fee tables, so run your own SKUs through the Fee Preview report in Seller Central before you plan a big shipment. The peak-season jump is the number to remember: the same cubic foot costs about three times as much from October to December. A slow product that is cheap to hold in the spring can be expensive by December.

Limits on how much you can send

Amazon caps how much stock you can send in. In 2023 it announced a single monthly capacity limit, set in cubic feet, announced in the third full week of each month in the Capacity Monitor. It also shows estimated limits for the next two months, and says limits are influenced by your IPI score, sales forecasts, shipment lead time and warehouse capacity. Sellers can ask for more space by naming a reservation fee. Amazon's current FBA page still calls these restock limits and warns that going over may raise storage costs, so check the Capacity Monitor in your account for the live rules.

IPI, the Inventory Performance Index, is a 0 to 1,000 score of how well you balance stock. Amazon says it needs a Professional plan. Sell-through, a part of it, is units sold and delivered in 90 days divided by your average sellable units.

Tracking FBA stock

In Seller Central, open Inventory and then FBA Inventory. Amazon says the dashboard shows what feeds your IPI score and storage use, with prompts to restock or create outlet deals, and it shows shipment status with alerts such as missing tracking IDs. The same tool has a Fix Stranded Inventory page and an inventory age filter.

Watch four numbers every week:

• Available units you can sell today.
• Inbound units on their way to Amazon.
• Days of supply. Amazon calls stock excess when it is over 90 days of supply compared with demand.
• Stranded units, meaning stock with no active listing.

Reimbursements for lost or damaged stock

Amazon has a reimbursement policy for stock it loses or damages in its buildings, and the rules differ by case: warehouse loss, shipment to Amazon, customer returns and removals. The claim windows have changed in the past and are short for some cases, so read the current one before you rely on it. Open the FBA inventory reimbursement policy in Seller Central and read the window for each case. Then compare your shipped quantity to the received quantity monthly. The longer a gap sits, the harder it is to claim. Some paid tools run this check for you. sellerboard lists refunds for lost inventory on its plans, and the Seller 365 bundle from Threecolts, InventoryLab's owner, lists a reimbursement service that takes a commission (15% on its Standard plan, as of November 2026).

A spreadsheet layout that works

If you have under about 100 SKUs, one sheet is enough. One row per SKU, with these columns:

1. SKU, product name and ASIN (Amazon's own product number)
2. Units in your own warehouse
3. Units available at FBA
4. Units inbound to FBA
5. Units on other channels or at another warehouse
6. Total units (the sum of the four above)
7. Units sold in the last 30 days, all channels
8. Days of supply: total units divided by (sold last 30 days divided by 30)
9. Supplier lead time in days
10. Flag: red if days of supply is under lead time plus 14, or over 90

Update it from a weekly Amazon report download. If you want help pasting the sheet into Claude to find the red rows, my guide to catching FBA stock problems with AI has the exact prompts.

Tools compared

• Amazon's FBA Inventory tools. Free with the selling plan. They cover FBA only.
• sellerboard, a profit and inventory dashboard for Amazon sellers that also supports Shopify, Walmart and eBay (two other big online marketplaces). From $19 a month for up to 3,000 orders a month, as of November 2026.
• InventoryLab, a listing, shipment and stock tool for resellers. $69 a month, or $58 billed yearly, with a 30-day trial. Its Restocking Insights add-on is $25 a month. It shows FBA, merchant-fulfilled and unlisted stock in one view.
• Helium 10, a suite of Amazon research and operations tools. Platinum is $129 a month and Diamond is $359 a month. Its pricing page lists inventory management and profit and loss reporting on Diamond, and only limited profit reporting on Platinum.

Seeing FBA and other stock together

This is where most multichannel sellers struggle. Amazon's tools stop at the edge of Amazon. Your stock on Shopify (a tool for running your own online shop), Etsy (a marketplace for handmade and vintage goods) or wholesale lives somewhere else. There are three ways to fix it.

1. One master sheet. The layout above. It is free and enough for a small catalog.
2. Use Amazon to fulfill other channels. Amazon's Multichannel Fulfillment ships orders from your own site out of the same stock. Amazon's Warehousing and Distribution (AWD), a bulk storage service, can also supply other sales channels. That gives you one pool of stock, though you rely on Amazon for all of it.
3. A stock system that connects the channels. A tool or a small custom build that pulls each channel into one count. If this sounds like you, see tool stack for an ecommerce store and running several seller accounts on one system.

Amazon says AWD users on auto-replenishment pay no FBA storage-utilization, low-inventory or inbound-placement fees and avoid FBA capacity limits. It also says AWD storage can be 10% cheaper again with auto-replenishment. Check the current terms, because bulk storage adds a step and a second set of rules.

How I'd approach this

Start with the sheet. It takes an hour to build and teaches you which numbers you actually look at. Do the weekly check on the same day each week. Count your Q4 storage cost in October, not in December. Keep slow movers under 90 days of supply, and do the shipped-versus-received check once a month.

When you spend more than a couple of hours a week reconciling channels, or you have had an oversell, buy a tool. If none of them fit how you sell, that is when a small custom system pays off: Amazon, your site and your warehouse in one count, with alerts. Business process automation shows how to decide what to automate first.