What Is Amazon FBA? Costs, Steps and Real Math

Amazon FBA (Fulfillment by Amazon) is the program where you send your inventory to Amazon warehouses and Amazon stores it, picks it, packs it, ships it to the buyer and handles the return and the customer service for that order. You still own the stock. Amazon rents you the shelf and the labor, and bills you per unit sold and per cubic foot stored. So the useful answer to "what is Amazon FBA" is not the definition. It is the arithmetic: what leaves every sale, and on which date each rate starts.

How Amazon FBA works, step by step

1. You create the listing and set the offer to be fulfilled by Amazon.
2. You build an inbound shipment plan in Seller Central and send units to the fulfillment centers Amazon assigns.
3. Amazon receives and checks in the units. From that moment the stock is sellable, and from that moment it pays storage.
4. A customer orders. Amazon picks, packs and ships it, and the offer carries the Prime badge.
5. Amazon handles delivery, customer service and the return if the buyer sends it back.
6. The proceeds land in your balance and are released seven days after the delivery date under the current reserve setting.

Step 6 is the one that surprises people who came for the logistics. FBA changes who ships the box, and it also changes when the money is yours. The delivery date plus seven days payout policy is the reason a profitable FBA account can still run short of cash in the middle of a restock.

What Amazon FBA costs, with the date each rate starts

Four charges cover most of what an FBA seller pays. Two are fixed by policy, two move with your product.

The selling plan. The Professional selling plan is 39.99 USD per month in the United States store, flat, whatever you sell. Spread across 400 units a month that is 0.10 USD per unit. Spread across 40 units it is 1.00 USD per unit, which is usually the difference between a working SKU and a dead one.

The referral fee. Amazon takes a percentage of the total sales price on every order, FBA or not. Most categories sit at 15 percent, with a minimum referral fee of 0.30 USD per item in the US store. Some categories are lower and some are banded: Grocery and Gourmet is 8 percent up to a 15.00 USD sales price and 15 percent above it. Check your own category before you model anything.

The FBA fulfillment fee. This is the per unit charge for picking, packing and shipping. It is set by product size tier, which comes from the dimensions and weight of the unit as it is packaged and ready to ship, not from the dimensions of the product itself. For 2026, Amazon raised FBA fees by an average of 0.08 USD per unit sold, which it describes as less than 0.5 percent of an average item's selling price, effective January 15, 2026. That followed a year with no increase in US referral and FBA fees in 2025.

Monthly inventory storage. Charged on your daily average volume in cubic feet. For standard size units the rate is 0.78 USD per cubic foot from January through September and 2.40 USD per cubic foot from October through December. That is roughly three times the bill for the same box on the same shelf, and it starts on October 1, not on Black Friday. The Q4 rate is why what you leave in the warehouse in September decides your December storage invoice.

What does Amazon really keep per unit?

See my numbers

The full example, from sale to bank

Take one unit of a 25.00 USD product in a 15 percent referral category, standard size, 0.12 cubic feet packaged, selling 200 units a month.

• Sales price: 25.00 USD
• Referral fee at 15 percent: 3.75 USD
• FBA fulfillment fee: your size tier rate. Read it per SKU in the Fee Preview report in Seller Central rather than from any table you find outside Amazon, because the tier is decided by the packaged dimensions Amazon measured, not the ones you declared. Budget 0.08 USD more per unit than the 2025 figure you were using.
• Monthly storage, January to September: 0.12 cubic feet at 0.78 USD is 0.09 USD per unit per month held.
• Monthly storage, October to December: 0.12 cubic feet at 2.40 USD is 0.29 USD per unit per month held.
• Selling plan: 39.99 USD divided by 200 units is 0.20 USD per unit.

Before the fulfillment fee, that unit is already carrying 4.04 USD in January and 4.24 USD in November, on storage of one month. Hold it for four months into Q4 and storage alone goes from 0.09 USD to well over 1.00 USD per unit. The lever is not the rate. It is how long the unit sits.

What FBA does not cover

FBA is fulfillment. It is not merchandising and it is not a safety net.

• It does not fix your catalog. A suppressed or deactivated listing stays unsellable with full shelves behind it.
• It does not protect your metrics from your own supply gaps. Running thin triggers the low inventory level fee, and Amazon charges it on top of everything above.
• It does not guarantee reimbursement when units go missing on the way in or back. Those claims have windows, and the windows close.

What to check in your own account this month

1. Open the Fee Preview report and read the size tier and fulfillment fee Amazon has assigned to each SKU. Tiers change when Amazon remeasures.
2. Pull your storage fee report and sort by cubic feet held. Anything that will not sell through by December is buying shelf space at the Q4 rate.
3. Check your referral fee percentage per category, not per account. Banded categories catch people who changed price points.
4. Look at your reserve and your release dates before you commit to a purchase order, not after.

FBA is a good deal when your unit turns fast and a slow bleed when it does not. The rates above are public and dated. The only number that belongs to you is how many days each unit spends on Amazon's shelf.

“FBA fees will increase by an average of $0.08 per unit sold, or less than 0.5% of an average item's selling price.”

— Amazon Selling Partners ↗

#FBA#fees#Seller Central#guide

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