There is no universal winner. FBA usually wins for small, fast-moving, Prime-eligible SKUs, while FBM usually wins for large, heavy, slow-moving, custom, or brand-sensitive products. You are really trading fees against control, Prime conversion against margin, and operational work you outsource against work you keep. A per-ASIN framework and calculators follow below.
TL;DR:
- Price FBA’s size and weight fees, seasonal storage, returns, removal, and inbound placement against FBM labor, packaging, shipping, and restocking costs.
- Prime eligible listings often convert 20–30% higher than listings without Prime, but extra advertising can erase FBM’s cost savings when matching sales volume.
- Compare net profit per unit for each ASIN, including product cost, returns, conversion assumptions, and advertising needed to match Prime sales.
- Test new products with FBM, then send a small FBA pilot for proven sellers; retain FBM when packaging control or seasonal overflow matters.
- Keep inventory counts synchronized when splitting fulfillment or switching an ASIN, so your stock and Amazon’s inventory do not lead to overselling.
Table of Contents
- How do FBA and FBM compare side by side?
- What does each method actually cost?
- What work do you keep, and what do you hand off?
- How do you decide for each ASIN?
- When does a hybrid approach make sense?
- Which calculators and resources help you run the numbers?
- Why do I start with FBM and graduate winners to FBA?
- Where can you get a faster, guided path?
- FAQ
- Sources
How do FBA and FBM compare side by side?
With FBA, Amazon handles picking, packing, shipping, customer service and returns and your listing becomes Prime-eligible. With FBM, you or a 3PL store, pack, ship and support the order yourself, using Amazon’s tools but keeping control.
FBA pros:
- Prime badge and fast two-day delivery
- Customer service and returns handled by Amazon
- Scales without hiring warehouse staff
FBA cons:
- Per-unit fulfillment, storage and aging fees
- Less control over packaging and branding
- Inbound prep, labeling and shipment rules
FBM pros:
- Full control over packaging, inserts and brand experience
- No Amazon storage or aging charges
- Easy to test products with low upfront commitment
FBM cons:
- You carry labor, space and carrier costs
- Harder to win Prime-level conversion
- Customer service and returns land on you
In practice, small, lightweight, replenishable, high-velocity products favor FBA. Oversize, fragile, custom, slow-moving or brand-packaged items favor FBM.
What does each method actually cost?
Amazon separates selling fees from fulfillment costs. FBA costs include per-unit fulfillment based on size and weight, seasonal monthly storage, returns processing, removal or disposal, and inbound placement. Our FBA fees walkthrough helps you turn those line items into ASIN-level profit.
FBA buckets to price for every SKU:
- Fulfillment fee by size and weight tier
- Monthly storage, higher in peak season
- Long-term storage and aging charges for slow sellers
- Returns processing and removal or disposal
- Inbound placement and transport to the fulfillment center
FBM buckets to price just as honestly:
- Inbound shipping to your own storage
- Monthly warehouse or shelf rent
- Pick-and-pack labor and packaging materials
- Outbound carrier rates
- Returns handling and restocking
- Software and staffing
Hidden costs show up on both sides, including storage, removal charges, packaging, labor, shipping and returns, so a cheap-looking unit cost can mislead you.
Size and weight drive both sides, and seasonality inflates storage. Then add conversion. Industry analysis suggests Prime-eligible listings often convert 20–30% higher than non-Prime FBM listings. When FBM looks cheaper per unit, the extra PPC needed to match that conversion can erase the savings.
What work do you keep, and what do you hand off?
Under FBA, Amazon takes storage, picking, packing, shipping, returns processing and customer service. You keep product prep, labeling, inbound shipments and inventory planning. Run out of stock and sales stop, so forecasting matters more than most new sellers expect.
Under FBM, you keep everything: storage, picking, packing, shipping, customer service and returns. The seller or a 3PL handles those tasks, and many sellers outsource some or all of them while keeping control of packaging and branding.
Indirect costs deserve a line in your spreadsheet:
- Warehouse management or inventory software
- Labor hours and fulfillment errors, such as wrong items or late handoffs
- Brand packaging control, which FBA limits and FBM preserves
- Speed from first mile to last mile, which affects reviews
Our Amazon FBA step-by-step playbook covers the prep and inbound side in detail if you are leaning toward FBA.
How do you decide for each ASIN?
Decide at the ASIN level, not the account level. Here is the method:
- Gather inputs: size and weight, cost of goods, inbound shipping, estimated FBA fee, monthly storage estimate, sell-through rate, average sale price, return rate and current conversion rate.
- Calculate FBA net margin per unit: price, minus COGS, minus FBA fees, minus inbound and prep costs, minus expected returns cost.
- Calculate FBM net margin per unit: price, minus COGS, minus pick-and-pack cost, minus outbound shipping, minus packaging, minus returns handling, minus the added PPC needed to match Prime conversion.
- Run scenarios. Test conservative and aggressive conversion assumptions and estimate the ad spend required to equalize sales.
- Compare totals, then pick the method with the better net profit per unit and the healthier cash position.
Be careful with step 4. Lower unit cost under FBM means little if you need to buy your way back to the same sales volume.
Pro Tip: Launch new SKUs on FBM, then run a small FBA pilot before sending a big batch into Amazon fulfillment centers.
When does a hybrid approach make sense?
Many sellers split by SKU: FBA for fast movers and small items, FBM for oversized goods, seasonal overstock or bespoke products. It lets you protect margin where fees bite and protect conversion where Prime pays off.
Common uses:
- Keep FBM live as a Buy Box backup when FBA stock runs out
- Use FBM as overflow during peak season
- Test a new product on FBM before committing inventory to Amazon
- Move slow SKUs out of FBA to avoid long-term storage fees
When switching one ASIN, plan the inventory handoff carefully. Keep counts synced between your own stock and what sits at Amazon so you never oversell. Amazon documents the enrollment and inventory planning steps for moving a listing to FBA.
Which calculators and resources help you run the numbers?
Start with Amazon’s own tools and add outside benchmarks:
- Amazon Revenue Calculator: estimates fulfillment fees, storage and margin, and lets you compare FBA to self-fulfillment.
- Our calculator roundup: Amazon FBA calculators to cross-check fee and margin estimates.
- Shipping benchmarks: this guide to choosing a shipping partner explains carrier selection, which helps you estimate outbound FBM costs.
- Conversion drivers: Amazon SEO basics show how listing quality interacts with Prime conversion.
- Our fee guide: the FBA fees page for ASIN-level profit checks before you reorder.
Why do I start with FBM and graduate winners to FBA?
My recommendation is simple: do the per-ASIN math before you trust anyone’s blanket advice, including ours. Start untested products on FBM, move proven winners to FBA, keep brand-sensitive items on FBM, and use a hybrid during peak season. Most sellers overcommit to one method because it feels simpler, then pay for it in fees or lost conversion. Run the calculators and guides we linked, and let the numbers argue with your instincts.
— Nathaniel
Where can you get a faster, guided path?
Our Instant Course Access for Life is available for $97 one-off. Pair it with our FBA step-by-step playbook and fee calculators to put this decision framework to work on your own ASINs. Get Instant Course Access for Life.
FAQ
Should I do FBA or FBM?
It depends on the product. FBA usually fits small, fast-moving items where Prime conversion matters, and FBM fits large, slow or brand-sensitive items where you want control. Many sellers use both per product.
What does FBM stand for?
FBM stands for Fulfillment by Merchant. You, or a 3PL you hire, store, pack and ship orders and handle customer service, using Amazon tools while keeping control over packaging and inventory.
What are FBA logistics?
FBA logistics means Amazon stores your inventory in its fulfillment network, then picks, packs and ships each order. Amazon also handles customer service and returns and offers Prime two-day shipping on eligible listings.
Can FBA lower my shipping costs?
It can. Amazon says FBA can reduce shipping costs compared with retail carriers, and its two main cost types are storage and fulfillment. Always compare against your actual FBM carrier rates for each ASIN.
Sources
- Amazon FBA vs FBM: Which is right for you? – Sell on Amazon
- A guide to Amazon FBA fees | Sell on Amazon – Sell on Amazon
- Mcpanalytics
- 📦 FBA vs. FBM: Choose the Right Fulfillment Method for YOUR Business