One decision shapes almost every other aspect of your Amazon business: who fulfils the order? Choose Fulfilment by Amazon (FBA) and Amazon picks, packs, and ships for you. Choose Fulfilment by Merchant (FBM) and you handle it yourself. Both methods work — but they suit very different products, margins, and business stages.
This guide gives you a clear, honest comparison so you can make the right call for your specific situation in 2026.
FBA wins for most sellers at scale: it earns Prime eligibility, increases conversion rates, and dramatically reduces operational workload. FBM wins for heavy/bulky products, low-velocity SKUs, hazmat items Amazon won’t store, and sellers with existing fast fulfilment infrastructure.
How FBA Works
With FBA you send your stock in bulk to Amazon’s fulfilment centres. From that point, Amazon handles everything: storage, picking, packing, shipping, customer service, and returns. Your products earn the Prime badge automatically, which gives a significant conversion rate advantage — Prime buyers are Amazon’s highest-intent, highest-spend customer segment.
In return, Amazon charges you FBA fees on every sale: a fulfilment fee based on product dimensions and weight, plus monthly storage fees for inventory sitting in their warehouses. Long-term storage fees apply after 365 days.
How FBM Works
With FBM you list on Amazon but handle fulfilment entirely yourself (or via a third-party logistics partner). You receive the order notification, pick the product from your own warehouse, and ship it to the customer within your stated handling time.
You pay no FBA fulfilment fees, but you also bear all the warehousing, labour, packaging, and carrier costs directly. To earn the Prime badge as an FBM seller, you need to qualify for Seller Fulfilled Prime (SFP) — which requires proven fast dispatch rates and very strict performance metrics Amazon enforces tightly.
FBA vs FBM: The Full Comparison
| Factor | FBA | FBM | Winner |
|---|---|---|---|
| Prime eligibility | Automatic | Only via SFP (hard to qualify) | FBA |
| Conversion rate | Higher (Prime badge lifts CVR) | Lower (non-Prime listings convert less) | FBA |
| Buy Box wins | Strong advantage | Weaker unless SFP | FBA |
| Operational workload | Very low — Amazon handles it | High — you manage fulfilment | FBA |
| Fulfilment fees | Higher (FBA fee per unit) | Lower (only your carrier cost) | FBM |
| Storage cost | Monthly fee + long-term storage risk | Your own storage cost | Depends |
| Bulky / heavy products | FBA fees often prohibitive | Better unit economics | FBM |
| Slow-moving stock | Long-term storage fees accumulate | No storage fee risk | FBM |
| PPC performance | Better — Prime badge boosts CTR & CVR | Weaker — same ad spend, fewer conversions | FBA |
| Customer service | Amazon handles it | You handle it (or outsource) | FBA |
| Returns | Amazon processes automatically | You receive and process | FBA |
| Hazmat / restricted items | Many categories rejected by FBA | Full control | FBM |
| Inventory control | Limited — Amazon controls stock location | Full control | FBM |
| Seasonal stock risk | Q4 surcharges + storage limits | No seasonal surcharges | FBM |
The PPC Impact: Why FBA Usually Wins on Advertising
If you run Amazon PPC — and you should be — your fulfilment method directly affects your advertising performance. Here’s why FBA typically delivers better PPC results:
- Higher conversion rate: The Prime badge alone can lift conversion rates by 25–50% compared to equivalent non-Prime listings. The same keyword click converts at a higher rate, reducing your effective ACoS.
- Buy Box control: FBA sellers win the Buy Box more consistently. PPC ads only appear when your listing holds the Buy Box — lose the Box and your ads effectively stop running.
- Higher Click-Through Rate: Prime-badged products get more organic clicks on search results, improving your overall impression-to-sale funnel.
If an FBM listing converts at 8% and an FBA version of the same product converts at 12%, your ACoS on FBM is 50% higher for the same ad spend. On a tight margin product, that difference alone can flip a profitable PPC campaign into a loss-maker.
When FBM Genuinely Wins
FBA is not always the right answer. Here are the scenarios where FBM gives you a real edge:
Large, heavy, or oversized products
FBA fees scale with dimensions and weight. A garden furniture set or a treadmill can attract FBA fees of £25–80 per unit — making the model financially unworkable. FBM lets you negotiate freight rates and ship directly from your warehouse or a 3PL at far lower per-unit cost.
Restricted or hazmat categories
FBA rejects many products: lithium batteries above certain thresholds, aerosols, flammables, and various chemical products. If Amazon won’t store your product, FBM is the only option.
Very slow-moving or seasonal inventory
If your product sells 5–10 units a month, the monthly storage fees at Amazon’s fulfilment centres accumulate quickly — especially if stock sits over Q4 peak surcharge periods (October–December). FBM gives you complete control over storage costs for these SKUs.
Custom or made-to-order products
If you manufacture to order, there is no stock to pre-send to Amazon. FBM is the only logical choice, often combined with extended handling times made transparent in your listing.
You already have fast fulfilment infrastructure
If you run your own warehouse with next-day dispatch capability, and you qualify for Seller Fulfilled Prime, FBM can match FBA on Prime status while keeping more of your margin. This is a high-effort path but works well for established businesses with strong logistics.
The Hybrid Approach: FBA for Winners, FBM as Backup
Many experienced sellers run both simultaneously. The most common approach:
- FBA for your top-selling SKUs — high-velocity products where Prime eligibility and reduced operational load justify the fee
- FBM as a safety net — keeping FBM active on the same ASIN means you can still sell if FBA stock runs out at Amazon’s warehouse, avoiding a stock-out that tanks your organic rank
- FBM for slow movers and large items — listing these with FBM avoids long-term storage charges and oversized FBA fees
Always have an FBM offer sitting on your bestsellers, even if FBA is your primary method. If your FBA inventory runs dry during peak season — a common problem when sell-through accelerates unexpectedly — your FBM offer keeps the ASIN active and prevents your organic ranking from dropping.
FBA Fee Structure: What You’re Actually Paying (UK, 2026)
FBA fees in the UK are broken into two parts:
1. Fulfilment fees (per unit sold)
Charged on every item shipped. Calculated on the greater of the product’s actual weight or dimensional weight, across four size tiers:
- Small (under 300g) — approximately £2.50–£3.20 per unit
- Standard (300g–2kg) — approximately £3.20–£4.80 per unit
- Large standard (2kg–30kg) — approximately £4.80–£8.50 per unit
- Oversize — £10.00+ per unit depending on dimensions
2. Storage fees (per cubic foot per month)
Charged monthly on inventory sitting in Amazon’s warehouse. Standard storage: approximately £0.54/cubic foot January–September, rising to £0.81/cubic foot October–December. Long-term storage surcharges apply after 365 days.
You can calculate your exact FBA fees using Amazon’s FBA Revenue Calculator in Seller Central — always run this before committing to FBA for a new product.
How to Decide: A Decision Framework
Ask these questions in order:
- Does FBA fee + storage still leave you with a healthy margin? If your product can absorb FBA fees and still deliver 30%+ net margin, FBA is usually the right call.
- Is your product eligible for FBA? Check restricted categories and hazmat rules before planning your business around FBA.
- Are you selling more than 15–20 units per month? Below this velocity, FBM operational overhead may be manageable and storage fee risk lower.
- Is your product heavy or oversized? Run the FBA calculator. If fees exceed 20% of your selling price, FBM almost certainly wins on economics.
- Do you have fast, reliable fulfilment capability? If you can dispatch next-day consistently, FBM + SFP is worth pursuing for the right products.
For most new sellers launching a standard-size product under 2kg in a competitive category: start with FBA. The Prime badge and operational simplicity let you focus on what actually grows revenue — your advertising and listings — rather than logistics.
The Bottom Line
FBA is the better default for most sellers because it earns Prime eligibility automatically, converts better, wins the Buy Box more reliably, and eliminates the operational complexity of running your own fulfilment. These advantages compound directly into better PPC performance: the same ad spend generates more conversions at a lower ACoS.
FBM wins when your product economics don’t work with FBA fees (typically heavy or bulky items), when Amazon won’t store your product category, when your inventory moves slowly, or when you’re an established business with world-class logistics infrastructure that qualifies for Seller Fulfilled Prime.
The most sophisticated sellers run both — using FBA for their top performers and FBM as a backup and overflow channel that keeps the ASIN alive when FBA inventory runs low.
Not Sure Which Fulfilment Model Fits Your Products?
Book a free Amazon account audit with StoreStride. We’ll review your product economics, current fulfilment setup, and PPC performance — then give you a plain-English recommendation.