Methodology

Calculator rules

• Use transparent formulas.
• Show assumptions clearly.
• Keep calculations educational, not advisory.
• Test formulas before release.
• Do not store personal financial inputs by default.

Review process

Each calculator includes a last-reviewed date. Formulas should be checked after major product updates and at least quarterly for active production use.

Formula tests

The package includes a browser-based formula test page at /tests/formula-tests.html.