Amazon FBA vs FBM: The Cost Comparison That Decides

Amazon FBA vs FBM is not a question about logistics. It is a question about which costs you control and which ones Amazon sets for you. The referral fee is identical either way. Everything after it is where the decision lives.

FBA means Fulfillment by Amazon: your units sit in Amazon's fulfillment centers and Amazon picks, packs, ships and handles customer returns. FBM means the merchant fulfills: the unit sits in your warehouse or your third party's, and you ship it yourself. Amazon calls this Fulfilled by Merchant, and in reports and the API you will also see it as MFN, merchant fulfilled network.

What is identical in FBA vs FBM

Two costs do not move when you switch fulfillment.

The referral fee. Amazon charges it on the total sales price of every order, on FBA and FBM alike. It is 15% in most categories, lower in some (8% on the portion of Grocery and Gourmet Food sales up to $15, 8% on Baby, Beauty and Health and Personal Care items priced at $10 or less), with a minimum referral fee of $0.30 per item. Nobody escapes it by shipping their own boxes.

The selling plan. The Professional selling plan costs $39.99 per month regardless of fulfillment. The Individual plan charges $0.99 per item sold instead. The break even is arithmetic: $39.99 divided by $0.99 is 40.4, so Professional is cheaper from 41 units a month, which is why Amazon frames the choice around 40 items.

What only FBA charges you

A per-unit fulfillment fee by size tier. The rate depends on the product size tier and weight, and Amazon publishes the table in its 2026 fee reference. Two things to hold onto: the rate is per unit shipped, and it moves once a year. For 2026 Amazon announced an average increase of $0.08 per unit sold, less than 0.5% of an average item's selling price, effective January 15, 2026, with no new FBA fee types and at least 90 days of notice. The increase is not flat: small standard-size products priced $10 to $50 go up $0.25 per unit, small standard-size above $50 go up $0.51, and large standard-size above $50 go up $0.31 on average. 2025 carried no increase at all, which is the context most comparisons leave out.

Monthly inventory storage. This is the cost that decides Q4. Standard-size storage is $0.78 per cubic foot from January to September, down from $0.87 since April 1, 2024, and $2.40 per cubic foot from October to December. FBM pays none of it. You pay your own rent instead, which is usually flatter and always yours to negotiate.

Inbound and removal work. Getting units into the network and out of it again is FBA-only: inbound placement, removals, disposals. FBM has no equivalent because the unit never left your building.

Is FBA still cheaper for your SKUs?

Compare my costs

The numbers, end to end

Take a standard-size unit that sells at $30 and measures 0.3 cubic feet packaged, and say you hold 500 of them.

The referral fee is the same on both sides. 15% of $30 is $4.50 per unit. Write it down once and stop comparing it.

Storage is where the gap opens. 0.3 cubic feet at $0.78 is $0.234 per unit per month, so 500 units cost $117 a month from January to September. The same 500 units cost $360 a month from October to December, because the rate goes to $2.40. That is $243 of extra cost per month for inventory that did not move, sitting in the quarter when you most need it there.

Then add the per-unit fulfillment fee, from the size tier table for your product, plus $0.08 on average from January 15, 2026. Against that, put your real FBM cost for the same unit: the carrier label you actually pay, plus the minutes someone spends picking and packing it, plus the returns you process yourself.

The decision rule falls out of it. FBA wins when your own shipping and labour per unit is higher than the fulfillment fee, and when your units turn fast enough that storage stays small. FBM wins on slow movers, on anything bulky, and on anything you would otherwise be storing through October, November and December at $2.40 per cubic foot.

What FBM costs you that does not show on an invoice

Prime. An FBM offer is not Prime eligible on its own. The only route is Seller Fulfilled Prime, and it is a performance contract: SFP sellers must keep a cancellation rate of no more than 0.5% and an on-time shipment rate of at least 99.0% on Prime orders, thresholds in force since July 31, 2018, and enrollment runs through a 30 day trial you have to pass. Read the SFP program policy before you plan around it.

Your own metrics. With FBA, late deliveries are Amazon's problem. With FBM, on-time delivery, valid tracking and cancellation rates are yours, and they feed account health directly. Our guide to the Amazon account health rating explains what falls apart below 200.

Customer service and returns. FBA absorbs them. FBM does not.

How to actually decide, per SKU

Not per business. Per SKU, and per season.

1. Pull your unit economics with the Revenue Calculator and the Fee and Economics Preview report, both of which Amazon updates with the 2026 rates. The full FBA fee list with dates is the other half of that picture.
2. Split your catalogue by turn. Anything that will still be in a fulfillment center on October 1 is a storage decision, not a fulfillment decision: see what Q4 FBA storage really costs.
3. Check the floor, not just the ceiling. Going too thin on FBA stock has its own charge, explained in why you are being charged a low inventory level fee.
4. Run both. Nothing stops a catalogue from being FBA on fast movers and FBM on the rest, and most mature accounts are exactly that.

If you are still new to the FBA side of the comparison, start with what Amazon FBA is and what it costs, then come back to this with your own numbers.

The short version: FBA buys you Prime and your weekends, and charges you rent for both. FBM gives you the rent back and hands you the metrics.

#FBA#FBM#fees#fulfillment

👋Hey! We're the SellerKey Team

Data & product at SellerKey.co

📊 We build SellerKey.

The team behind SellerKey. We write about fees, margin, inventory and ads for Amazon sellers.

Our articlesContact us

← Previous

Amazon Lost My FBA Inventory and Never Reimbursed Me

Next →

Why Is My Buy Box Suppressed by an External Price?