FBA vs FBM: The Fundamental Tradeoff
Amazon offers two fulfillment models:
- FBA (Fulfillment by Amazon): Amazon stores, packs, and ships your products. You pay per unit + storage.
- FBM (Fulfillment by Merchant): You store, pack, and ship. You keep more margin but handle logistics.
The question isn't "which is better"—it's "which is more profitable for YOUR products?" The answer depends on:
- Product weight & dimensions
- Turnover rate (how fast it sells)
- Selling price
- Your operational capacity
- Seasonality
FBA Cost Breakdown
Fulfillment Fees (Per Unit Sold)
Charged when item ships. Varies by size/weight tier:
| Size Tier | Weight Limit | Fulfillment Fee |
|---|---|---|
| Small Standard | Up to 10 oz | $2.41 |
| Large Standard | Up to 20 oz | $3.19 |
| Small Oversize | Up to 70 oz | $4.39 |
| Large Oversize (1) | Up to 300 oz | $7.99 |
| Large Oversize (2) | Up to 900 oz | $12.39 |
| Special Oversize | 900+ oz | Calculated per unit |
Monthly Storage Fees (Per Cubic Foot)
Charged for inventory stored at Amazon fulfillment centers.
- Standard-Size Items: $0.87 per cubic foot/month (Jan-Sep)
- Oversize Items: $0.42 per cubic foot/month (Jan-Sep)
- Peak Season (Oct-Dec): $2.88 per cubic foot/month (standard), $1.23/cu ft (oversize)
How to calculate: Length × Width × Height ÷ 1,728 = cubic feet
Long-Term Storage Fees (Per Unit)
Charged after item stored 365+ days:
- Standard-Size: $6.90 per unit
- Oversize: $13.80 per unit
Charged every 90 days if item remains unfulfilled (e.g., Day 365, Day 455, Day 545)
Removal & Disposal Fees
- Removal fee: $0.50 per unit (if you remove inventory)
- Disposal fee: $0.25 per unit (if you request Amazon dispose)
Returns Processing
- Amazon handles returns; processed as refund to customer
- You're charged the fulfillment fee again on the return (if refunded)
- No explicit return fee, but lost product cost
Referral Fees (Non-FBA Specific but relevant)
- Amazon takes % of sale (6-45% depending on category)
- Example: Electronics 8%, Clothing 17%, Books 15%
- Same whether FBA or FBM
FBM Cost Breakdown
1. Storage & Warehouse Space
- Home/garage (free): $0 (if you have space)
- Spare bedroom office: $0 (but limits capacity)
- Small storage unit (5×10): $100-150/month
- Medium storage unit (10×20): $200-300/month
- Warehouse space: $0.50-1.50 per sq ft/month
2. Packing Materials
- Boxes: $0.50-1.50 per box
- Bubble wrap/padding: $0.20-0.50 per unit
- Packing tape: $0.05 per unit
- Labels/stickers: $0.05 per unit
- Total per unit: $0.80-2.50 (depends on product)
3. Shipping Costs
- USPS Priority Mail (under 1 lb): $4-7
- USPS Priority Mail (1-3 lbs): $7-12
- UPS Ground (1-10 lbs): $8-20 (varies by distance)
- FedEx Ground (1-10 lbs): $8-20
Pro tip: Negotiate rates after shipping 100+ packages/month
4. Labor Costs
- Your time: ~5-10 minutes per order (picking, packing, labeling, weighing)
- Wage value: If paying yourself $30/hour, that's $2.50-5 per order in labor
- Outsourced labor: $10-15 per order if hiring someone
- Packing service: $2-3 per box (send pre-sold inventory)
5. Additional Costs
- Inventory management software: $50-200/month
- Shipping label software: $10-30/month
- Quality control/inspections: $0.25-0.50 per unit
- Returns processing: $0.50-1.50 per return (relabeling, restocking)
5. Referral Fees (Same as FBA)
- Amazon still charges referral % (same as FBA)
- Your fulfillment advantage is you avoid fulfillment fees, not referral fees
Real Cost Comparison Examples
Product 1: Small Electronics (Earbuds)
Selling Price: $50
FBM FULFILLMENT (Same Product)
Winner: FBA by $6.09 per unit (22% higher profit)
Why? Small, light products have low FBA fees but high relative shipping costs for FBM.
Product 2: Medium Book
Selling Price: $25
FBM FULFILLMENT (Same Product)
Winner: FBA by $3.01 per unit (31% higher profit)
Product 3: Large Heavy Item (Tire Pressure Gauge Kit)
Selling Price: $35
FBM FULFILLMENT (Same Product)
Winner: FBA by $9.01 per unit (95% higher profit!)
Why? Heavy items have disproportionately high FBM shipping costs. FBA wins big.
When FBA Wins vs When FBM Wins
| Condition | FBA Better | FBM Better |
|---|---|---|
| High volume (100+ units/month) | ✓ FBA more efficient | |
| Low volume (under 10 units/month) | ✓ FBM from home is cheaper | |
| Heavy/bulky items | ✓ Storage fee less than shipping cost | |
| Small/light items | ✓ Lower fulfillment fees | |
| Fast turnover (weekly sales) | ✓ Storage fees low, efficiency high | |
| Slow turnover (months to sell) | ✓ Avoid storage fees | |
| High return rate (10%+) | ✓ Amazon handles returns | |
| Seasonal demand spikes | ✓ Control over storage space | |
| Need Prime badge for sales | ✓ Prime only with FBA |
The Prime Badge Factor
Critical Point: FBA products are Prime-eligible. FBM products are NOT.
Conversion rate impact: Prime-eligible products typically convert 10-30% better.
This alone can offset FBA fees for many products.
Example: 100 units/month at $50
FBM without Prime: 2% conversion = 2 sales = $100/month net
FBA with Prime: 3% conversion = 3 sales = $150/month net (after FBA fees)
Hybrid Strategy: Product Selection
- High-margin, light items: FBA (maximize volume with Prime)
- Low-margin, light items: FBM (avoid fees eating into thin margin)
- Heavy items: FBA (shipping too expensive for FBM)
- Slow-moving items: FBM (avoid storage fees)
- Seasonal items: FBM (don't tie up cash in off-season storage)
Summary: FBA vs FBM Decision Framework
✓ Use FBA if: Light/heavy ratio is good, volume is high, margin supports fees, conversion boost matters
✓ Use FBM if: Margins are thin (under 30%), volume is low, items move slowly, you have operational capacity
✓ Test both: List some products FBA, others FBM; track profitability
✓ Calculate true profit: Don't assume FBA wins; run the numbers for YOUR products