Both GPA and CGPA are computed using the credit-weighted average formula: GPA / CGPA = Σ(Ci × GPi) / Σ(Ci), where Ci represents the credits allotted to course i, and GPi is the grade point scored in that course. GPA applies to a single semester, while CGPA aggregates all registered courses across all completed semesters.

Under R2021 / R2017, the letter grades are O (10), A+ (9), A (8), B+ (7), B (6), C (5), and U (0). Under the updated R2025 regulation, the letter grade nomenclature follows S (10 - Superior), A (9), B (8), C (7), D (6), E (5), and U (0).

As per standard Anna University conversion guidelines, the equivalent percentage is estimated using: Percentage (%) = (CGPA − 0.5) × 10. For example, a CGPA of 8.00 yields (8.00 − 0.5) × 10 = 75.0%.

Generally, students with 75% or higher (CGPA ≥ 8.00) who cleared all courses in the first attempt within the minimum prescribed duration earn First Class with Distinction. Students securing 60% to 74.9% (CGPA 6.50 to 7.99) are awarded First Class, while 50% to 59.9% (CGPA 5.50 to 6.49) earns Second Class.

A 'U' (Re-appear) grade carries 0 grade points, but the course credits remain in the denominator (Σ Ci). This lowers the semester GPA. Once the course is cleared in a subsequent attempt, the updated grade point replaces the zero to recalculate cumulative CGPA.