Every manufacturer who starts selling on Amazon hits this fork in the road within the first month. Do you ship orders yourself (Fulfilled by Merchant, or FBM), or do you send inventory to Amazon's warehouses and let them handle it (Fulfilled by Amazon, or FBA)?
The internet is full of advice on this. Most of it comes from e-commerce gurus who've never set foot in a manufacturing facility. Their answer is almost always FBA — "let Amazon handle it so you can focus on growing your business." Which sounds great until you look at the actual numbers.
The right answer depends entirely on what you make, how you make it, and what your warehouse already looks like.
The Fee Breakdown Nobody Wants to Do
Take a product that sells for $39.99 on Amazon, weighs 1.5 lbs, and measures 10" x 6" x 4" (standard size). Here's what each model actually costs per unit:
| Cost Component | FBA | FBM |
|---|---|---|
| Amazon referral fee (15%) | $6.00 | $6.00 |
| FBA fulfillment fee | $5.40 | $0 |
| FBA monthly storage (avg) | $0.35 | $0 |
| Your shipping cost (est.) | $0 | $6.50 |
| Your packing labor (est.) | $0 | $1.50 |
| Total fulfillment cost | $11.75 | $14.00 |
At first glance, FBA wins by $2.25 per unit. And for a lot of sellers, that's where the analysis stops. It shouldn't.
The Costs That Don't Show Up in the Fee Calculator
Inbound shipping to Amazon. You have to get your products to Amazon's fulfillment centers. That's freight shipping — either LTL pallets or small parcel. For a manufacturer shipping from a single location to Amazon's distributed network, inbound shipping typically runs $0.50-$2.00 per unit depending on weight and distance. Amazon's partnered carrier program helps, but it's not free.
Long-term storage fees. Amazon charges $6.90 per cubic foot for inventory stored over 271 days (as of 2025). If your product has seasonal demand or you overestimate sell-through, these fees eat you alive. One manufacturer got hit with a $4,200 long-term storage bill because they sent too much inventory ahead of a holiday season that underperformed.
Removal and disposal fees. If you need to pull inventory back from Amazon — maybe you're discontinuing a SKU, or a batch has a quality issue — Amazon charges $0.97-$1.78 per unit for removal. For a manufacturer who discovers a batch problem and needs to recall 500 units from FBA, that's $485-$890 just to get your own product back.
Commingling risk. Unless you specifically opt out (and most sellers don't know to), Amazon may commingle your inventory with the same product from other sellers. A customer could receive a counterfeit or lower-quality version of your product that another seller sent to the same FBA warehouse. Your brand takes the hit. For manufacturers who control their own quality, this is a serious risk.
When you add inbound shipping ($1.00 avg), the realistic FBA cost per unit is $12.75, not $11.75. The gap narrows to $1.25.
Where FBM Actually Wins for Manufacturers
Manufacturers already have a warehouse. They already have staff. The marginal cost of packing an e-commerce order in an existing facility is lower than the fully loaded cost in the table above.
If your warehouse team is already there — packing wholesale orders, managing production output, handling inventory — adding e-commerce fulfillment is incremental work, not a new operation. The $1.50 packing labor estimate assumes dedicated labor for e-commerce. In reality, many manufacturers absorb e-commerce packing into existing workflows at a lower effective cost.
And then there are the advantages that don't show up in a per-unit cost comparison:
Batch and Lot Control
This is the big one. When you fulfill orders yourself, you control which batch ships to which customer. You can enforce FIFO rotation, ensure products with the longest remaining shelf life go out first, and maintain complete traceability from production line to customer doorstep. With FBA, you lose all of that. Amazon doesn't track your batch numbers. If you need to recall a specific production run, good luck figuring out which FBA customers received units from that batch.
Quality Control at the Point of Shipment
A scan-driven packing system lets you verify every item before it ships. Wrong item? The scanner catches it. Damaged packaging? The operator sees it. With FBA, Amazon's warehouse workers are packing thousands of different products from hundreds of sellers. Your product doesn't get special attention.
Brand Experience
When you pack orders yourself, you control the unboxing experience. Custom packaging, branded inserts, thank-you cards, product samples — all of these build brand loyalty and drive repeat purchases. FBA ships everything in Amazon's brown boxes. Your brand is invisible.
Shipping Cost Optimization
When you control shipping, you can use multi-provider rate shopping to compare rates across carriers and aggregators for every single shipment. That $6.50 average shipping cost in the table? With rate shopping, manufacturers regularly bring it down to $5.00-$5.50. Now FBM is cheaper than FBA on a per-unit basis.
The Buy Box Myth
"But you need FBA to win the Buy Box!" This is the most repeated piece of Amazon advice, and it's only partially true.
Yes, FBA sellers have an advantage in Buy Box eligibility. But FBM sellers with strong metrics — on-time shipping above 97%, low defect rate, fast handling time — compete effectively. Amazon's algorithm weighs price, shipping speed, and seller performance. An FBM seller offering the same product at a lower price with 2-day shipping and a 99% on-time rate can absolutely win the Buy Box.
The key is operational execution. If your FBM operation ships late, has high defect rates, or can't offer competitive delivery speeds, FBA is the safer choice. But if you invest in proper warehouse automation — barcode verification, structured workflows, reliable carrier partnerships — FBM performance metrics match or exceed FBA.
The Hybrid Approach That Actually Makes Sense
For most manufacturers, the answer isn't purely FBM or purely FBA. It's a hybrid:
Use FBA for your top 3-5 SKUs that have consistent, predictable demand. These are your volume drivers where FBA's speed and Prime badge generate meaningful incremental sales. Keep inventory levels tight — 4-6 weeks of supply — to avoid long-term storage fees.
Use FBM for everything else. New products (demand is unpredictable), seasonal items (storage fees will kill you), high-value items (you want quality control), and anything with batch tracking requirements. This is probably 70-80% of your catalog.
Use FBM as your FBA backup. When FBA inventory runs out, FBM listings keep you selling while replenishment ships to Amazon's warehouses. No lost sales during the gap.
This hybrid model gives you Prime visibility on your best sellers while maintaining control, traceability, and cost efficiency on the rest of your catalog.
The Numbers at Scale
The math for a manufacturer doing 800 Amazon orders per month with an average order value of $39.99:
| Scenario | Monthly Cost | Annual Cost |
|---|---|---|
| 100% FBA (incl. inbound) | $10,200 | $122,400 |
| 100% FBM (with rate shopping) | $9,200 | $110,400 |
| Hybrid (20% FBA / 80% FBM) | $9,400 | $112,800 |
The annual difference between 100% FBA and 100% FBM is $12,000. The hybrid model saves $9,600 versus full FBA while keeping Prime visibility on your top sellers.
These aren't huge numbers individually. But for a manufacturer operating on 15-20% net margins, $12,000 in annual savings is equivalent to $60,000-$80,000 in additional revenue. That's real money.
Making the Switch
If you're currently 100% FBA and considering a shift to FBM or hybrid, here's the practical sequence:
Week 1-2: Set up your FBM fulfillment workflow. This means a packing station, a barcode scanner, shipping accounts with at least two carriers, and an order management system that handles multi-channel orders.
Week 3-4: Start FBM on your lowest-volume SKUs. These are low-risk — if something goes wrong, it affects few orders. Dial in your handling time, packing process, and carrier pickup schedule.
Week 5-8: Expand FBM to medium-volume SKUs. Monitor your seller metrics closely — on-time delivery, valid tracking rate, defect rate. These need to stay green.
Week 9-12: Evaluate which high-volume SKUs to keep on FBA versus move to FBM. Base the decision on margin impact, batch tracking needs, and whether the Prime badge meaningfully affects conversion for that specific product.
Don't rush it. Amazon's algorithm penalizes sellers who switch fulfillment methods and then perform poorly. Better to take three months and do it right than to flip everything overnight and tank your metrics.
The Decision Framework
Skip the spreadsheet for a minute. Answer these three questions:
Do you need batch or lot traceability? If yes, FBM is the only option that gives you control. FBA doesn't track your batches. Period.
Is your warehouse already staffed? If yes, the marginal cost of FBM is lower than the fee comparison suggests. You're paying those people anyway.
Are you selling products that look similar? If yes, scan-driven packing verification prevents wrong-item shipments that FBA's generic warehouse workers won't catch.
If you answered yes to any of those, FBM (or hybrid) deserves serious consideration.