How Amazon FBA Sellers Lose 15-20% of Margin to Hidden Import Costs

If you sell imported products on Amazon FBA, your real margin is almost certainly lower than you think. Not by a little. By 15-20 percentage points.

The naive margin calculation

Here's how most sellers estimate their profit:

Selling price ($25.00) minus product cost ($6.25) minus Amazon referral fee ($3.75) = $15.00 profit (60% margin)

That looks great. But it's dangerously incomplete.

What's actually missing

Between your supplier's factory and your customer's doorstep, at least six cost layers eat into that margin:

1. Ocean freight allocation: $0.80-1.50 per unit depending on product size and shipment volume
2. US customs duties (MFN rate): varies by HS code, typically 0-25% of declared value
3. Section 301 tariffs: additional 7.5-25% on China-origin goods (on top of MFN duties)
4. IEEPA surcharge: additional 20%+ on China-origin goods (as of 2025)
5. Customs brokerage: $0.15-0.40 per unit when allocated across the shipment
6. Amazon FBA fees: fulfillment + storage + inbound placement, often $5-8 per standard-size unit

The real math

That same $25.00 product with all costs included:

• FOB cost: $6.25
• Freight (ocean, allocated): $1.10
• Duties (MFN 3.4% + Section 301 25% + IEEPA 20%): $3.03
• Customs brokerage: $0.25
• Amazon referral (15%): $3.75
• FBA fulfillment: $4.75
• Storage (monthly avg): $0.35
• True total cost: $19.48
• True margin: $5.52 (22.1%)

That 60% margin was actually 22%. The difference is the cost waterfall that most sellers never calculate.

Why this matters for product decisions

At 60% margin, almost any product looks profitable. At 22%, you need to ask harder questions: Can you negotiate a lower FOB? Is there an HS code with a lower duty rate? Would sourcing from Vietnam instead of China eliminate the Section 301 tariff layer entirely?

These are the questions MarginStack helps you answer, with real tariff data from government sources, not estimates.