Methodology
Calculations should be inspectable.
EasyTry separates fee rules, arithmetic, interface, and explanatory content so every estimate can be traced and tested.
Official sources first
Default rates come from platform-owned help centers or pricing pages. Competitor calculators are used for product research, never as the authority for a fee rule.
Versioned rules
Every production ruleset records its platform, market, category, effective period, source URL, and last verification date. If a rule cannot be confirmed, it is not silently used as a default.
Money and rounding
Core calculations use integer cents and basis points. Individual fee components are rounded to the nearest cent before totals are added. Reverse calculations search cent by cent for the lowest price that reaches the requested target.
Tests before publication
We test zero values, negative profit, threshold boundaries, progressive rate tiers, per-order fees, international exceptions, and reverse-price minimality. Display code does not own the fee formula.
Limits of an estimate
Marketplace statements can include taxes on fees, refunds, credits, optional services, negotiated rates, or account-specific adjustments that are not known to this calculator. EasyTry is a planning tool, not an invoice or accounting record.