What Is Amazon FBA and FBM? The Two Cost Models

Amazon FBA and FBM are the two ways to deliver an Amazon order, and the difference that decides your margin is not the warehouse: it is which charges attach to the unit. FBA (Fulfillment by Amazon) means Amazon stores your inventory in its fulfillment centers, picks it, packs it, ships it and takes the customer return. FBM (Fulfilled by Merchant, which Amazon also calls the Merchant Fulfilled Network) means the ASIN sells on Amazon and you ship it yourself, from your own stock, with your own carrier.

Both models pay the Amazon referral fee on every sale. After that they stop looking alike, and in 2026 they separated further.

What is Amazon FBA in cost terms

Under FBA you buy a bundle of services and you pay for each one separately:

• A per-unit fulfillment fee, set by size tier and weight.
• Monthly inventory storage, charged per cubic foot and higher in the last quarter of the year.
• An inbound placement service fee, which Amazon introduced on March 1, 2024 and reduces or waives depending on how many receiving locations your shipment splits into.
• A low-inventory-level fee on standard-size products, which the same announcement says you avoid by keeping more than four weeks of inventory relative to sales.
• A returns processing fee on products with the highest return rates in their category.

Two 2026 changes land on top of that list, and both are FBA only.

The first is the 3.5% fuel and logistics-related surcharge. It started on April 17, 2026 for FBA and Remote Fulfillment with FBA in the US and Canada, and on May 2, 2026 for Buy with Prime and Multi-Channel Fulfillment. It is calculated on the fulfillment fee, not on the sale price, and Amazon put the US FBA average at about 0.17 dollars per unit.

The second is the holiday peak fulfillment fee. Amazon's holiday 2026 fee announcement sets the window at October 15, 2026 to January 14, 2027, an average of 0.32 dollars per unit above non-peak rates, and states that the 3.5% surcharge applies on top of the peak fee.

Separately, the 2026 update to US referral and FBA fees raised FBA fees by an average of 0.08 dollars per unit sold. The announcement is explicit about when: "Unless otherwise noted, all changes will be effective January 15, 2026." It also says no new fee types were planned for 2026 and that sellers get at least 90 days of notice before an increase.

What is Amazon FBM in cost terms

Under FBM you pay Amazon for the sale and nothing for the logistics. No fulfillment fee. No monthly storage fee. No inbound placement fee. No low-inventory-level fee. No 3.5% surcharge and no peak fee either, because there is no fulfillment fee for them to be calculated on.

What you pay instead is real and it is yours to control: your warehouse, your packaging, your carrier contract, the labor to pick and pack, and the return trip when the customer sends it back. None of it appears on your Amazon fee report, which is exactly why FBM margins look better on screen than they are in the bank.

FBM also carries an operational cost that FBA absorbs. Your delivery performance is your own: late shipments and tracking defects sit on your account health, not on Amazon's.

The charges that only one model pays

Which of your units pay the peak fee?

See my numbers

A full example: 1,000 units in the peak window

Take a standard-size unit you already ship through FBA, and count only what 2026 added, using Amazon's own averages:

1. The 2026 fee update added 0.08 dollars per unit from January 15, 2026.
2. The fuel and logistics surcharge added about 0.17 dollars per unit from April 17, 2026.
3. The peak window adds an average of 0.32 dollars per unit between October 15, 2026 and January 14, 2027.

A unit sold in December 2026 therefore carries about 0.57 dollars of FBA cost that the same unit did not carry in December 2025. On 1,000 units that is about 570 dollars. And because the surcharge is a percentage of the fulfillment fee rather than a flat amount, the 3.5% piece grows while the peak fee is in force.

The FBM version of that same unit pays none of those three. It pays your carrier instead. The comparison is only honest when you price your own shipping, packaging and labor per unit and put that number next to the FBA total. Our cost comparison of Amazon FBA and FBM runs that calculation side by side.

Returns: two different safety nets

This is the part most FBA and FBM comparisons leave out, and it is where the money actually moves.

Both models share the customer-facing return rules. Amazon's extended holiday return window lets customers return items bought between November 1 and December 31, 2026 until January 31, 2027 (January 15, 2027 for Apple products), and it applies whether the order was fulfilled by Amazon or by you.

What differs is what you can claim back.

Under FBA you claim through the FBA inventory reimbursement policy. Amazon's eligibility windows for reimbursement claims put customer returns claims at 45 to 105 days after the refund or replacement date, with filing before day 45 not allowed, and fulfillment center loss or damage claims at 60 days from the date the item was reported. Since March 10, 2025, inventory lost or damaged before a customer order is reimbursed on manufacturing cost rather than sale price, while loss after an order is still reimbursed at the order's sale price minus fees.

Under FBM you claim through SAFE-T, which covers seller-fulfilled orders only. Amazon cut that window from 60 days to 30 effective February 16, 2026, counted from the return delivery scan at your warehouse or the refund date, whichever is later.

So FBA gives you a longer claim window and an automated reimbursement flow, and FBM gives you a 30-day clock that starts without announcing itself. Neither safety net is automatic in practice. Both need somebody reading the report.

Which model fits your product

The decision is per ASIN, not per account.

• Small, light, fast-selling units usually win on FBA, because the fulfillment fee beats any carrier rate you can negotiate at that weight and Prime delivery lifts conversion.
• Heavy, bulky or slow-selling units usually win on FBM, because FBA charges you twice for slowness: storage every month, plus the peak rate if the units are still there in the last quarter.
• High-return-rate categories need the returns processing fee in the FBA column before you compare anything else.
• Anything you cannot forecast is safer on FBM during the peak window, because an unsold unit sitting in a fulfillment center in December pays peak rates for the privilege.

Plenty of accounts run both on the same ASIN: FBA for the volume, FBM as the backup when FBA inventory runs out. That is a supported setup, and it is also the one that makes fee reporting hardest to read.

What to check in your own numbers

Do not take the averages above as your numbers. Amazon publishes averages. Your profit and loss statement has units.

1. Pull the Fee Preview report and the Revenue Calculator for your top ASINs. Amazon says both were updated for the 2026 rates and for the surcharge.
2. Put your real FBM cost per unit next to the FBA total: carrier rate, box, labor, and the share of returns you ship back.
3. Check which of your units are still in a fulfillment center during the peak window. Our guide to Amazon FBA fees and the date each one starts lists every charge with its effective date, and what percentage Amazon FBA takes from a sale shows the full waterfall on a single unit.

If you only need one side of the definition, we cover what Amazon FBA is and what FBM means on Amazon separately. The useful version is the one above: the same referral fee, two different cost stacks, and a 2026 calendar that only touches one of them.

“Unless otherwise noted, all changes will be effective January 15, 2026.”

— Amazon Seller Central ↗

#fba#fbm#fees#amazon-seller

👋Hey! I'm Amara

Press at SellerKey.co

☕ Espresso. Never a latte macchiato.

I cover Amazon fee and policy changes: what changed, when it applies and where Amazon published it.

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