A visible calculation model
Each calculator states its formula and keeps assumptions visible beside the inputs. Platform defaults are starting values rather than hidden facts, and users can override rates to match their market, category and account.
Versioned rules and sources
Platform-specific presets are stored separately from calculation code with a source URL, effective date and verification date. A new rule receives a new version instead of silently overwriting the historical assumption.
- Official pricing and policy pages are the primary sources.
- Automated monitors detect source changes but do not publish fee changes without review.
- Representative test cases compare expected results before deployment.
Rounding and currency
Internal calculations use JavaScript numeric precision and round only for display unless a carrier rounding rule is an explicit input. Currency selectors format values; they do not perform foreign-exchange conversion.
Corrections
If a preset or formula appears incorrect, send the calculator URL, market, expected result and official source through the contact address. Confirmed corrections are tested and recorded with a new review date.
Last updated: July 18, 2026