Why Standard Profit Calculators Fail US Sellers
Most generic margin calculators ignore the real-world deductions that eat 10% to 25% of net margin in 2026:
- TikTok Shop Creator Sample Ghosting: Free samples mailed to affiliates who never post a video must be amortized into active unit COGS.
- Return-Rate Shipping Erosion: An 18% apparel return rate wastes outbound and return shipping labels even when referral fees are refunded.
- Sales Tax Fee Drag (eBay & Whatnot): Fees apply to the full checkout total including buyer-paid shipping and US state sales tax.
Core Break-Even Formulas Used
1. Net Profit Before Ads
Retail Price − Landed COGS − Outbound Shipping − Platform Referral & Payment Fees − Affiliate Commission − Expected Return Loss2. Break-Even ROAS
Retail Price ÷ Net Profit Before AdsIf your ad campaigns (GMV Max, Meta, Google, Etsy Ads) return below this ROAS multiple, every incremental order loses cash.
3. Editable Assumptions Notice
Pre-calibrated niche defaults reflect typical 2026 US category averages. Every input field is 100% editable to match your exact Seller Central or 3PL invoice.
2026 Official Marketplace Fee Schedule & Data Sources
Default platform fee formulas on SellerROAS.com are calibrated against the official US seller documentation listed below. Always verify category-specific exceptions in your seller dashboard.
| Marketplace | Baseline 2026 US Fee Structure | Official Documentation | Verified |
|---|---|---|---|
| TikTok Shop US | 6% referral fee (most categories) + 2%–15% creator affiliate commission | TikTok Shop US Seller University — Commission & Fee Policy | November 2026 |
| Etsy US | $0.20 listing + 6.5% transaction + 3% + $0.25 Etsy Payments (+ 12%/15% Offsite Ads) | Etsy Seller Handbook — Fees & Payments Policy | November 2026 |
| Shopify DTC | 2.9% + $0.30 (Basic), 2.6% + $0.30 (Shopify), 2.4% + $0.30 (Advanced) | Shopify US Pricing & Payments Schedule | November 2026 |
| Amazon FBA US | 8%–17% category referral fee + size/weight-tier FBA pick & pack fee | Amazon Seller Central US — 2026 FBA Fulfillment & Referral Fees | November 2026 |
| Whatnot Live US | 8% marketplace commission + 2.9% + $0.30 payment processing (on item + shipping) | Whatnot Help Center — Seller Fees & Payouts | November 2026 |
| eBay US | 13.25%–13.6% Final Value Fee (on item + shipping + sales tax) + $0.30/$0.40 per order | eBay US Seller Center — Selling Fees | November 2026 |
| Walmart WFS US | 6%–15% category referral fee + Walmart Fulfillment Services weight-tier fee | Walmart Marketplace — Referral & WFS Fee Schedule | November 2026 |