How We Calculate Fees
This is an independent calculator project. Every number on the site comes from a platform's own fee page — never from another calculator.
Official sources only
Each rate rule stores the URL of the official page it was read from and the date it was verified. On the site, that becomes the Verified 2026-10-18 ↗ chip next to the number — click it and land on the source. We never copy figures from other calculators, aggregators, or AI summaries, and we don't use redirect pages: one line, one link, straight to the platform.
Category-level precision
Most fee calculators apply a single percentage to everything. Real platforms don't work that way. We model:
| Case | Modeled behavior |
|---|---|
| eBay women's handbags | 15% up to $2,000 → 9% above |
| eBay jewelry / watches | tier switches above $5,000 / $1,000 |
| eBay per-order fee | $0.30 ≤ $10 · $0.40 > $10 (both tiers) |
| Etsy Offsite Ads | 15% / 12% by annual volume · capped $100/sale |
| StockX payment | 3% with $5 minimum — modeled on low-price items |
A real fix: older calculators bill trading cards at the 13.6% general rate; the official rate is 13.25% up to $7,500 — on a $2,400 card that is an $8.40 error per sale, and those add up over a year.
What we don't model
Honesty about boundaries: we do not model one-off platform promotions beyond flagged limited-time terms, negotiated enterprise rates, or tax outcomes. Scope notes: Etsy payment processing is modeled for US sellers only (non-US Etsy Payments rates are out of MVP scope — this site is US-first); Depop sellers outside the UK/US/Australia pay PayPal's processing fee, which Depop does not publish per region — we show PayPal's published US commercial rate (3.49% + $0.49) marked approximate; currency conversion spreads (PayPal 3%/4%, documented from the official merchant-fee schedule) are disclosed but not auto-applied to calculations. When something is unverified it ships labeled, never silently guessed.
Regression tests
Every rate release is checked against hand-worked examples at known boundaries — $10, $150, $1,000, $2,000, $5,000, $7,500, $15,000 — plus tax-base rules (buyer shipping and sales tax in the fee base), Whatnot's $1,500 promo line and 4-week tiers, StockX's $5 minimum, and Depop's US 0% row. The suite runs at build time and in the engine's unit tests; a mismatch blocks the release.
Update cadence
Quarterly re-crawls of every source URL, plus immediate version bumps when a platform announces a change. Every change lands in the fee changes log with a version number — the rates you saw last month are retrievable, not overwritten.
Methodology describes fee calculation only; nothing here is tax, legal, or financial advice.