Calculator Methodology

Source selection

We prioritize official pricing pages, fee schedules, help-center policies, and regulatory notices. Every calculator exposes its source links and the date of the approved snapshot.

Rule modeling

• Percentage, fixed, threshold, category, weight, and format rules are represented separately.
• Optional programs are optional inputs rather than silently included costs.
• User-entered product, shipping, advertising, tax, and compliance costs remain separate from platform rates.
• Displayed totals use the selected scenario and do not predict future policy changes.

Review and limitations

A rule is published only after review. Because platform documentation and seller-specific contracts can change, results are planning estimates rather than invoices or professional advice. Always compare the result with the seller dashboard and current official terms.