Marketplace Financial Utility
E-Commerce Fee & Net Margin Auditor
Calculate exact marketplace commission, fulfillment fees, and net profit margins across Amazon FBA, Etsy, and TikTok Shop. Audit single products or bulk-audit entire catalog CSVs.
Every figure is calculated in your browser. No product costs, catalog data or margins are transmitted or stored.
1. Target Marketplace
Amazon FBA Tier Specs
Itemized Platform & Fulfillment Deductions
Bulk Catalog CSV Margin Auditor
Upload product catalog CSV to flag loss-making SKUs in local memory
| SKU / Item | Platform | Retail | Fees | Net Profit | Margin | Status |
|---|---|---|---|---|---|---|
Ergonomic Laptop Stand SKU-89201 | amazon | $39.99 | -$11.45 | $16.84 | 42.1% | Profitable |
Ceramic Pour-Over Dripper SKU-89202 | etsy | $28.00 | -$3.42 | $16.38 | 58.5% | Profitable |
Magnetic Phone Mount SKU-89203 | tiktok | $15.99 | -$6.26 | $5.23 | 32.7% | Profitable |
Stainless Steel Water Bottle 32oz SKU-89204 | amazon | $18.99 | -$9.80 | $0.69 | 3.6% | Low Margin |
Printed Cotton Canvas Tote SKU-89205 | etsy | $12.00 | -$4.50 | $-0.30 | -2.5% | Loss |
2026 Marketplace Fee Structures Compared
| Platform | Referral / Commission | Fulfillment / Shipping | Payment Processing | Key Margin Trap |
|---|---|---|---|---|
| Amazon FBA | 8% – 15% ($0.30 min) | $3.22 – $6.55+ (weight/size based) | Included in referral fee | Q4 storage surge & oversized dimensional tiers |
| Etsy | 6.5% transaction fee | Merchant self-fulfillment | 3.0% + $0.25 per transaction | 15% Offsite Ads fee applied automatically on ad sales |
| TikTok Shop | 6.0% + $0.30 fee | Merchant or TikTok FBT | Included in commission | 10%–20% creator affiliate commissions on viral videos |
How to use this tool
Choose the marketplace and category
Amazon FBA, Etsy or TikTok Shop. The category sets the referral fee — consumer electronics is 8% where most categories are 15%.
Enter price, cost and shipping
Selling price, cost of goods and inbound freight. These give the gross margin before any marketplace takes its cut.
Add packaged dimensions and weight
Amazon bills fulfilment on the packaged unit, not the product. A fraction of an inch can push you into the next size tier and change the fee.
Read net margin and break-even
The breakdown itemises referral, fulfilment and storage fees, then gives net profit per unit and the price floor below which you lose money.
Frequently Asked Questions
How do I prevent Amazon FBA size tier jumps from destroying my profit?
Amazon measures packaged unit dimensions, not the product itself. If your packaging expands during folding or transit past 15" × 12" × 0.75", the item shifts from Small Standard ($3.40) to Large Standard ($4.75+), eroding $1.35 in pure margin per sale. Use rigid poly bags or tuck-in boxes that ensure dimensions remain safely below the threshold.
Can I opt out of Etsy Offsite Ads?
If your shop has earned less than $10,000 USD in any consecutive 12-month period, you can opt out of Etsy Offsite Ads in your Shop Manager settings. Once your shop crosses $10,000 in trailing 12-month sales, participation becomes mandatory at a discounted 12% fee rate.
Are my catalog margins and supplier costs private?
Yes, 100%. All computations, COGS analyses, and CSV catalog audits execute strictly inside your local browser memory via client-side JavaScript. Zero catalog records or proprietary supplier costs are ever uploaded to any server.
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