FBA (Fulfilled by Amazon) means Amazon stores your inventory and handles picking, packing, shipping, and customer service. FBM (Fulfilled by Merchant) means you store and ship your own inventory and manage the logistics yourself. Both are open to third-party sellers, and most sellers we work with run both at once across different products.
The choice is not a philosophy. It is a math problem you solve one SKU at a time. Below we walk through the tradeoffs the way we would if we were sitting with your Seller Central account: fees, Prime, Buy Box, control, margin, cash flow, and product fit.
FBA vs. FBM: How Do They Compare Side by Side?
Here is the short version before the detail. The table maps the dimensions that actually move a fulfillment decision. Read it once, then use the sections below to pressure-test the two or three rows that matter for your catalog.
| Dimension | FBA (Fulfilled by Amazon) | FBM (Fulfilled by Merchant) |
|---|---|---|
| Who fulfills the order | Amazon warehouse staff | You or your 3PL |
| Inventory location | Amazon fulfillment centers | Your warehouse or 3PL |
| Prime eligibility | Automatic on all FBA listings | Not by default. Requires Seller Fulfilled Prime approval |
| Fees paid to Amazon | Per-unit fee by size tier and weight, plus monthly storage | None to Amazon. You pay your own shipping and storage |
| Buy Box advantage | Favored by the algorithm when other factors are equal | Must compete harder on price or seller metrics |
| Returns handling | Amazon processes returns under its standard policy | You manage returns directly |
| Customer service | Amazon handles post-order inquiries | You handle all customer service |
| Control over fulfillment | Low. Amazon controls packaging and handling | High. You control every step |
| Cash flow | Capital tied up in inventory sitting at Amazon | Ship as orders come in, closer to demand |
| Best fit | Small, fast-moving products. Sellers who want Prime without the overhead | Large, heavy, slow-moving, or custom products. Sellers with their own logistics |
How Does FBA Work?
With FBA, you ship inventory to Amazon’s network in advance. When an order comes in, Amazon picks, packs, ships, handles returns, and answers customer questions. You pay for this through per-unit fulfillment fees, set by size and weight, plus monthly storage fees based on the space your units occupy. Amazon says shipping with FBA costs 70% less per unit than comparable premium options from other major US carriers. (Source: Amazon Seller Blog)
The real draw is Prime. FBA products qualify for Prime automatically, with 2-day and often same-day or next-day shipping, and you do not run the operation. That matters because a large share of buyers filter by Prime. Standard FBM listings are excluded from that filter, so those shoppers never see them.
FBA also processes returns under Amazon’s standard policy, credits the buyer, and either restocks or disposes of the unit based on your settings. You can set removal orders for units you want back, or request disposal for the rest.
How Does FBM Work?
With FBM, you store inventory at your own warehouse, a 3PL, or home, and you ship directly when orders land. You set the shipping speeds and rates on your offer, and you have to hit them. Amazon holds FBM sellers to performance standards: a late shipment rate below 4%, a pre-fulfillment cancellation rate below 2.5%, and a valid tracking rate at or above Amazon’s published threshold.
Standard FBM listings are not Prime-eligible. You can apply for Seller Fulfilled Prime and offer the Prime badge while shipping from your own facility, but the bar is high: same-day or next-day cutoffs, strong on-time delivery, supported carriers, and a trial period with volume thresholds. Amazon reviews SFP eligibility periodically and can pull it if you slip on the metrics.
What Does FBA Cost Compared to FBM?
What Are the FBA Costs?
FBA sellers pay Amazon’s referral fee on every sale, which is category-dependent and typically runs 6 to 20% of item price. On top of that sit the FBA-specific fees below. We list them because the ones sellers forget are the ones that quietly erase margin.
- Fulfillment fees: A per-unit charge for pick, pack, and ship, based on size tier and shipping weight. Amazon updates the schedule annually and publishes current rates in Seller Central.
- Monthly storage fees: Charged per cubic foot at the fulfillment center. Standard rates run January through September, then rise sharply in Q4 when warehouse space is tight.
- Long-term storage fees: A surcharge on units sitting in FBA for 365 days or more, charged per unit per month.
- Removal and disposal fees: A per-unit charge to pull inventory out of FBA. Disposal costs less than removal.
FBA economics work best when a product sells fast, is small and light, and is priced high enough that the fees are a reasonable slice of revenue. When any one of those breaks, the fees start eating the margin.
What Are the FBM Costs?
FBM sellers still pay Amazon’s referral fee, but they carry their own fulfillment costs. What those add up to depends entirely on your setup:
- Warehouse or storage rent
- Labor for picking, packing, and shipping
- Outbound shipping, negotiated with carriers or through a 3PL
- Packaging materials
- Returns handling and processing
For a small seller shipping from home, FBM often beats FBA on large, heavy, slow, or low-margin products. At scale, the answer turns on your negotiated carrier rates versus Amazon’s, and Amazon’s rates carry the weight of its volume discounts. This is where we do the math per SKU rather than trust a rule of thumb.
Does FBA or FBM Win the Buy Box?
FBA carries a structural edge in Buy Box competition. Amazon’s algorithm treats fulfillment method as a factor, and FBA, because it guarantees fast shipping and Prime, is generally favored over standard FBM when everything else is equal. To take Buy Box share from an FBA competitor, an FBM seller usually has to give ground on price or run cleaner account metrics.
Search visibility follows the same pattern. FBA listings show up in Prime-filtered searches. A meaningful share of buyers filter by Prime, and without SFP, an FBM listing is invisible to them. The exact share varies by category, but the direction does not.
When Does FBA Make Sense?
FBA is usually the better call when Amazon’s network lowers your per-unit cost, or when Prime lifts conversion enough to pay for the fees. Amazon reports that Buy with Prime raises conversion by an average of 25%, which is a fair proxy for what the Prime badge is worth. (Source: Amazon Seller Blog) We reach for FBA when we see:
- Small, light products where Amazon’s discounted shipping likely beats your own carrier rates.
- High-velocity products that turn over fast and never sit long enough to rack up storage fees.
- Sellers who want Prime without taking on the operational load of Seller Fulfilled Prime.
- Sellers with no warehouse who do not want to build a fulfillment operation from scratch.
- Products with heavy returns or service needs that are painful to handle in-house.
When Does FBM Make Sense?
FBM is usually the better call when a product’s size, weight, or slow velocity makes FBA fees too big a share of the margin, or when you already run competitive logistics. We reach for FBM when we see:
- Large, heavy, or oversize products where FBA fulfillment fees swallow the margin.
- Slow-moving or seasonal inventory where long-term storage fees or IPI score pressure makes FBA a bad deal.
- Perishable or temperature-sensitive products that FBA cannot store.
- Custom or made-to-order products that need your hands on them before they ship.
- Sellers with their own warehouse whose in-house cost per unit already beats FBA.
- Products needing special handling that Amazon’s standard process does not accommodate.
There is a cash-flow angle here too. FBA ties up capital in inventory sitting at Amazon ahead of demand. FBM lets you ship closer to the order, which keeps more cash free. For a thin-margin catalog, that difference is not a footnote.
Can You Run Both FBA and FBM at Once?
Yes, and most sellers we work with do. You can list the same ASIN with an FBA offer and an FBM offer at the same time. The common use is inventory protection: if FBA stock runs out, the FBM offer keeps selling while you replenish. The FBM offer usually will not hold the Buy Box while FBA stock is live, because FBA is favored, but it works as a safety net during a stock-out.
Across a large catalog, we tend to put high-velocity core products in FBA and push slow-movers or large-format items to FBM or a 3PL. The optimal model can differ by ASIN inside the same catalog, so the allocation only holds up if you know per-SKU profitability under each model. Guessing by volume is how good products end up in the wrong bucket. Our services and the terms in our glossary both start from that per-SKU math.
This is the same idea we cover when sales climb but profit stays flat: the fulfillment fees hide inside revenue that looks healthy. Tools that calculate true unit economics by ASIN, fulfillment fees included, let you sort FBA from FBM on margin data instead of intuition.