Add Grade Calculators (gradecalculators.io)

[waydelyle]

What changed and why

Adds Grade Calculators to Focus, Productivity & Study Planning.

Students enter assignment scores and syllabus weights to see current class/letter grade and the score needed on the final exam. Fits the study-planning job alongside planners and trackers already in this category.

Inclusion criteria

1. Helps learners plan and track class performance (weighted grades + final-exam target).
2. Active HTTPS canonical page: https://gradecalculators.io/
3. Free web tool for individual students; no account required.
4. Concrete learning use beyond a marketing landing page.
5. Neutral description verified from the site title/meta description.

Checked

• Searched catalog/tools.json — no existing grade/GPA calculator listing
• python3 scripts/format_catalog.py
• python3 scripts/render_catalog.py
• python3 scripts/validate_catalog.py
• Categories: focus-productivity-study-planning; access free; ai_role none

Affiliation

I am Wayde Lyle (@waydelyle), owner of gradecalculators.io. maintainer_affiliated is false (not a StudyArena maintainer product).