What Does Amazon FBM Mean? Costs, Metrics and Math

Amazon has two ways to put your unit in a customer's hands: Amazon ships it, or you do. If you are asking what Amazon FBM means, it is the second one. FBM stands for Fulfilled by Merchant: you hold the stock, you pack the box, you buy the label, and you answer for the delivery date. The sale still happens on Amazon, and Amazon still charges its referral fee on it.

The listing does not change. The accountability does.

What Amazon FBM means on the offer itself

FBM is a property of the offer, not of your account. The same ASIN can carry an FBA offer and an FBM offer at the same time, each on its own SKU.

In Seller Central the fulfillment channel reads "Fulfilled by Merchant". In Amazon's reports and in the Selling Partner API the same offer is tagged MFN, the merchant fulfillment network, while a unit sitting in a fulfillment center is AFN. If you have ever wondered why a report says MFN and your screen says Fulfilled by Merchant, that is why: two names, one channel.

Three things stay with Amazon when you sell FBM:

• The referral fee on the sale.
• The detail page, the reviews and the customer.
• The Featured Offer decision. In the Featured Offer eligibility update Amazon lists what the selection weighs: total price, delivery speed, free shipping, free returns, seller performance and stock availability. Fulfillment method is not one of those factors, so an FBM offer competes for the Featured Offer on the same terms as an FBA one.

Three things move to you: the shipping cost, the customer service, and the delivery metrics.

What FBM costs that FBA does not

The FBA charges disappear. The 2026 fee update that Amazon published on October 15, 2025 raised FBA fulfillment fees by an average of $0.08 per unit sold from January 15, 2026, and added no new FBA fee types. None of that reaches an FBM offer, and neither does monthly FBA storage.

What replaces them is your own box, your own label and your own time. And one charge that surprises sellers who move an ASIN to FBM: the referral fee is calculated on the total sales price, which Amazon's fee schedule defines as "the total amount paid by the buyer, including the item price, and any delivery or gift wrapping charges". A seller quoting that schedule in a Seller Forums thread on referral fees spells out the consequence.

So the shipping you charge is part of the referral base:

• Item at $24.00, shipping at $6.00. Total sales price: $30.00.
• The referral fee is calculated on $30.00, not on $24.00.
• Raise the shipping charge to $9.00 and you have raised the referral base to $33.00, before a carrier has touched the box.

Rates vary by category and by price tier, so the percentage that applies to you is the one in your category's fee schedule. Our breakdown of what percentage Amazon FBA takes from a sale walks the same waterfall for the FBA side.

Is your delivery promise holding up?

See my metrics

The number that decides whether FBM survives: 90%

This is the part that catches sellers who treat FBM as the cheap option.

Since September 25, 2024, Amazon requires a minimum On-Time Delivery Rate of 90% "without promise extensions" to keep seller-fulfilled products listed on Amazon.com. Amazon's own on-time delivery policy announcement also recommends 95% or greater, and it is explicit about who carries the risk: "sellers are not responsible for on-time delivery promises for FBA orders".

Read that the other way round and you have the whole point of FBM. On an FBA order, a late delivery is Amazon's problem. On an FBM order, it is yours, and it is measured.

What the 90% floor looks like on a real account:

• You ship 300 FBM units inside a 14 day window.
• 90% of 300 is 270. You can be late on 30 units.
• Unit 31 puts the seller-fulfilled offers below the minimum.

Thirty late units sounds like a lot until a carrier has one bad week in December. That is why peak season, not January, is when FBM accounts fall under the floor. What happens next is covered in how an OTDR deactivation hits the offer rather than the account.

What FBM means for your margin

The honest summary: FBM trades a fee you can predict for a cost you control and a metric you own.

• You keep the fulfillment margin, and you absorb the carrier's bad days.
• You decide the packaging, and you pay for the mistake if it arrives broken.
• You set the shipping charge, and you pay the referral fee on it.
• You see the delivery promise, and Amazon measures whether you kept it.

If the question behind "what does FBM mean" is really "should I move this ASIN", the numbers that decide it are side by side in our FBA vs FBM cost comparison. If you are starting from zero, what Amazon FBA is and what it costs is the other half of the same decision, and the Amazon seller account fee applies to both channels either way.

One last thing worth knowing before you switch: Amazon does not reuse an FBA offer as an FBM offer. Sellers who swap the channel in place report the listing going dark while the change settles, which is why the usual advice is a second SKU for the second channel instead of a conversion.

“sellers are not responsible for on-time delivery promises for FBA orders”

— Amazon Seller Central, on-time delivery policy ↗

#FBM#FBA#Seller Central#OTDR

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