How we check fees

Every calculator is built from the marketplace's own help and fee pages, never from other calculators or blog posts. Each calculator page lists the exact official pages used and the date they were last checked.

Our process

1. Read the marketplace's official fee pages and record the rate, what it is charged on (item price, shipping, sales tax), and any caps or minimums.
2. Encode the rules and test them against worked examples.
3. Re-check sources regularly and whenever a marketplace announces a fee change, then update the "checked" date.

Limits

Results are estimates. Marketplaces round differently, apply promotions, and change rules by category, seller level or region. Sales tax varies by buyer location. Always confirm a fee on the marketplace before relying on it. Found a mistake? Every calculator has a "Spotted a wrong or outdated fee?" box under its sources. We check every report against the official page.