Most sellers think they know their profit per SKU. Almost none of them actually do — because the calculation involves at least eight cost lines, and Amazon hides three of them in different reports. Here's the exact formula, the gotchas, and a worked example.
The formula
For a given SKU over a given period:
Net Profit = (Gross Revenue − Refunds − Promotional Rebates)
− (Amazon Selling Fees + FBA Fees + Other Fees)
− (Unit Cost × Units Sold)
− Inbound Shipping Allocation
− Storage + Long-Term Storage + Removal Fees
− (Overhead Allocation: PPC, software, etc.)
+ FBA Inventory ReimbursementsDivide by units sold to get profit per unit. Divide net profit by gross revenue to get net margin.
Where each number comes from
| Line | Source |
|---|---|
| Gross revenue, refunds, promos | UTR product sales + promotional rebates columns |
| Selling, FBA, other fees | UTR fee columns |
| Unit cost | Your purchase invoices |
| Inbound shipping | Freight invoices ÷ units shipped |
| Storage fees | UTR Service Fee rows, type = storage |
| Overhead | PPC reports, software receipts, allocated by SKU revenue share |
| Reimbursements | UTR FBA Inventory Reimbursement rows |
Worked example
One month for a single SKU, "Wireless Earbuds A":
- Units sold: 120
- Gross revenue: $4,800
- Refunds: −$240 (5%)
- Promotional rebates: −$300 (Lightning Deal)
- Selling fees (15% referral): −$684
- FBA fees ($3.50/unit × 120): −$420
- Unit cost ($12 × 120): −$1,440
- Inbound shipping ($0.40/unit × 120): −$48
- Storage fees (allocated): −$25
- PPC spend on this SKU: −$300
- Reimbursements: +$60
Net profit: $1,403 → $11.69/unit → 29.2% margin on gross.
Most sellers stop at "revenue minus Amazon fees minus unit cost" and get $1,956 — overstating profit by 39%. That's the kind of error that turns a "winning SKU" into a loss-maker once you scale ad spend.
Why doing this manually fails
Three pitfalls:
- Storage fees aren't per-SKU in the UTR — they're per-ASIN-per-month rollups. You have to map them back yourself.
- PPC allocation drifts. If you only spent on one campaign but it covered five SKUs, dividing equally is wrong; you need impression share or revenue share.
- Refunds lag. A refund issued in July belongs to a June sale. Bucketing by transaction date misstates both months.
Skip the spreadsheet
The Seller Reports tool runs the formula above automatically the moment you upload your UTR and a unit-cost file. See it on real data in the demo, or try the free single-SKU calculator if you want to model one product first.
FAQ
What about marketplace facilitator tax?
Don't include it. Amazon collects and remits it on your behalf — it flows through your statements but never lands in your pocket. Treat it as a pass-through.
How do I allocate inbound shipping?
Sum the freight invoice, divide by total units in the shipment, and apply that per-unit cost as long as those units exist in inventory. When the shipment is sold through, reset.
Should I use cash or accrual?
Accrual (bucketing by order date, not transaction date) gives a cleaner monthly picture. Cash matches your bank deposits. Pick one and stick to it.