How to Calculate Your True Per-Unit Cost on Amazon FBA — A Complete Fee Breakdown

1. Start With Your Product Cost (COGS)

Your Cost of Goods Sold (COGS) is the foundation of your Amazon FBA per unit cost calculator. It's what you actually pay your supplier for one unit — but it includes more than the sticker price.

Here's what to include in COGS:

• Unit price from the supplier (negotiated rate, not MOQ list price)
• Packaging costs (poly bags, boxes, inserts, barcode labels)
• Inspection fees divided across the order (typically $100–$300 per inspection)
• Sample costs spread across your first batch
• Supplier-side modifications (logo printing, custom packaging)

Example: You order 500 units at $4.20/unit. Inspection costs $150 ($0.30/unit). Custom packaging is $0.40/unit. Your real COGS is $4.90/unit, not $4.20.

Beginners almost always forget packaging and inspections. Skipping these makes your margin look 10–15% better on paper than it really is. Build the habit now: every cost paid to your supplier or factory partner gets divided by total units and added to COGS.

2. Add Freight and Import Costs Per Unit

Once your product leaves the factory, you still have to get it to Amazon. These freight and import costs are often the second-largest expense after COGS, and they vary wildly depending on shipping method.

Costs to divide across your unit count:

• Freight charges (air, sea, or express)
• Customs duties (based on HTS code — usually 0–25%)
• Customs broker fees ($100–$200 per shipment)
• Port and destination charges (drayage, ISF filing, bond fees)
• Trucking from port to Amazon FBA warehouse

Example: You ship 500 units by sea. Total landed freight + duty + brokerage = $1,200. That's $2.40/unit in shipping costs.

Quick rules of thumb:

• Sea freight: $1.50–$3.50/unit (slow, cheapest)
• Air freight: $4–$8/unit (faster, mid-range)
• Express (DHL/UPS): $6–$12/unit (fastest, expensive)

Add this number to your COGS to get your landed cost per unit. In our example: $4.90 + $2.40 = $7.30 landed cost. This is the number you should always use when evaluating profitability — never just supplier price.

3. Calculate Amazon's Referral and FBA Fees

Now we get to Amazon's cut. There are two main fees every FBA seller pays on every sale, and they can easily eat 30–40% of your selling price.

Referral Fee (Amazon's commission):

• Most categories: 15% of selling price
• Some categories lower (e.g., consumer electronics: 8%)
• Minimum referral fee: $0.30 per item

FBA Fulfillment Fee (picking, packing, shipping to customer) — based on size and weight:

• Small standard (under 1 lb): ~$3.25
• Large standard (1–2 lb): ~$4.75–$5.40
• Large standard (2–3 lb): ~$5.75–$6.50
• Large bulky and oversize: $9+ and climbs quickly

Example: You sell at $24.99. - Referral fee: $24.99 × 15% = $3.75 - FBA fee (1 lb product): $4.75 - Total Amazon fees: $8.50

Use the Amazon Revenue Calculator (free, inside Seller Central) to get exact fees for your product's dimensions. Plug in your ASIN or a competitor's, and Amazon shows you fulfillment fees instantly. Beginners should check this before sourcing — not after.

4. Don't Forget Storage, Returns, and Long-Term Fees

This is where most beginners get blindsided. The fees above only cover a clean, fast-selling product. Real life includes storage, slow inventory, and returns.

Monthly storage fees:

• Jan–Sep: $0.78/cubic foot (standard size)
• Oct–Dec: $2.40/cubic foot (Q4 surcharge)

Aged inventory surcharge (kicks in at 181 days): adds $0.50–$6.90/cubic foot on top of monthly storage.

Return processing fee: As of 2024, Amazon charges return fees on high-return-rate products in apparel, shoes, and several other categories.

Inbound placement fee: New in 2024 — $0.20–$1.50+/unit depending on how you split shipments to Amazon's warehouses.

Per-unit estimate to add to your calculator:

• Storage: $0.10–$0.40/unit/month for typical small products
• Returns reserve: budget 2–5% of revenue (higher in apparel)
• Inbound placement: $0.30–$0.75/unit average

Example continued: Add roughly $0.75/unit for storage, returns, and inbound placement combined. Conservative beginners should budget $1.00/unit to be safe.

Skipping these fees is the #1 reason new sellers think they're profitable but watch their bank balance shrink each month.

5. Put It All Together: Your True Per-Unit Cost Formula

Now combine everything into one clear formula you can use for any product.

True Per-Unit Cost Formula:

True Per-Unit Cost = COGS + Freight/Duty + Amazon Fees + Storage/Returns/Misc

Full example using our numbers:

• COGS (with packaging + inspection): $4.90
• Freight + duty per unit: $2.40
• Referral fee (15% of $24.99): $3.75
• FBA fulfillment fee: $4.75
• Storage + returns + inbound: $1.00
• Total per-unit cost: $16.80

Selling price: $24.99 Profit per unit: $24.99 − $16.80 = $8.19 Margin: 32.8%

Beginner targets to aim for:

• Minimum 25% net margin after all fees
• At least $5 net profit per unit (so PPC and price drops don't wipe you out)
• ROI of 50%+ on cash invested per unit

If your numbers don't hit these benchmarks, the product is too risky for a beginner. Renegotiate with your supplier, find a lighter/smaller version to lower FBA fees, or move to a different product. Never launch with margins under 20% — Amazon advertising alone will eat that up.

Conclusion

Your true per-unit cost on Amazon FBA is never just what the supplier charges. It's the combination of COGS, freight and duty, referral and FBA fees, plus storage, returns, and placement costs. Miss any of these, and your "profitable" product can quietly bleed money for months.

Key takeaways:

• Always calculate landed cost (COGS + freight + duty), not just supplier price
• Use the free Amazon Revenue Calculator to confirm fulfillment fees before sourcing
• Budget $0.75–$1.00/unit for storage, returns, and inbound placement
• Aim for 25%+ net margin and $5+ profit per unit as a beginner

Your next step: Open a spreadsheet right now, list every cost line from this article, and run the numbers on the product you're considering. If the math doesn't work on paper, it won't work on Amazon. Do this once and you'll save yourself thousands of dollars in mistakes — and start your FBA journey with real, verified profit.