GPA formula: GPA = Σ(Credits × Grade Points) / Σ(Credits). Each subject's contribution to GPA is weighted by its credit value. A 4-credit Operating Systems course with an A grade affects GPA twice as much as a 2-credit elective with the same grade. Grade points come from your university's letter-to-point mapping: typically A+/AA = 10, A = 9, B+ = 8, B = 7, C = 6, D = 5, E = 4, F (fail) = 0.
Three scales used in India: (1) 10-point: dominant in engineering colleges, B-schools, and most autonomous universities. (2) 7-point or 5-point: some older state universities. (3) 4.0 scale: international colleges, US-based programs, IB curriculum. Conversion from 10-point to 4.0: roughly GPA_4 = (GPA_10 / 10) × 4. So 8.5/10 ≈ 3.4/4. WES (World Education Services) provides the official conversion for visa and admission purposes.
Semester GPA (SGPA) vs Cumulative GPA (CGPA): SGPA is the GPA for one specific semester, considering only that semester's courses. CGPA is the running average across all semesters. CGPA = Σ(SGPA × Credits in semester) / Σ(Credits across all semesters). Both are important: CGPA represents overall standing; SGPA tracks semester-wise performance. Plan study time to keep SGPA above CGPA so CGPA keeps rising.