Our calculator quality standard

1. Calculation quality

• Inputs have explicit units and ranges.
• Formula logic is separated from presentation code.
• Known-answer examples are checked before release.
• Edge cases such as invalid or impossible inputs are handled.

2. Evidence and transparency

• Formula names and equations are shown where appropriate.
• Sources are linked from the page or reference section.
• Assumptions and limitations are visible.
• Last-reviewed dates are displayed.

3. UX and accessibility

• Semantic HTML is used for primary page structure.
• Form labels are associated with inputs.
• Images have descriptive alt text.
• Layouts are responsive and keyboard-friendly.

4. Trust and security

• HTTPS is used in production.
• No account is required for the calculators.
• Routine calculations are performed in the browser.
• Corrections and bug reports have a visible contact route.