Sources & Methodology

1. Source Selection Framework

We prioritize primary and authoritative references whenever possible:

• Government publications and official agency documentation.
• Academic and standards-based references.
• Well-established formula conventions used in practice.
• Provider documentation where calculator-specific rules apply.

2. Formula Implementation Rules

• Define explicit inputs, units, defaults, and allowed ranges.
• Implement deterministic formulas with typed logic.
• Handle rounding intentionally and format outputs clearly.
• Provide plain-language formula explanations where relevant.

3. QA and Verification

Before publication, calculators are checked with representative, boundary, and stress scenarios. We compare outputs against known examples or manual calculations when available.

We also test user experience behavior such as mobile input handling, real-time update performance, and error messaging clarity.

4. Category-Specific Reference Types

• Finance and payroll: official tax authority and payroll framework references.
• Health: widely accepted public health and clinical guidance context.
• Education: institution-specific and standards-based grading structures.
• Engineering and science: textbook and standards-aligned equations.
• Conversion/math: fixed mathematical definitions and conversion factors.

5. Known Limitations

Real-world systems can vary by jurisdiction, institution, employer, provider, and time. Calculator outputs may differ from official or contract-specific outcomes when local rules diverge from generalized assumptions.

6. Corrections and Source Requests

If you identify a formula issue or want source clarification, contact us through the Contact page. We prioritize correction requests that include reproducible examples.