Why simple grade averages can be wrong
GPA is usually a credit-weighted average, not the average of letter grades. A 3-unit course contributes more to the semester GPA than a 1-unit course because it represents more credit weight.
CGPA extends the principle across the courses included in the cumulative record. University rules govern whether repeated, transferred, deferred or excluded courses enter that calculation; check your result statement and applicable handbook.
Work through a semester example
For illustration only, use a five-point scale in which A = 5, B = 4 and C = 3. Multiply each course’s credit units by the applicable grade point; then add the quality points and divide by total credit units.
A complete example
- GST101: 2 credit units, A (5 points) → 2 × 5 = 10 quality points.
- CIT104: 3 credit units, B (4 points) → 3 × 4 = 12 quality points.
- MTH101: 2 credit units, C (3 points) → 2 × 3 = 6 quality points.
- Total units = 2 + 3 + 2 = 7. Total quality points = 10 + 12 + 6 = 28.
- Semester GPA = 28 ÷ 7 = 4.00. These course units/grades are illustrative, not student records.
Extend the calculation to CGPA
Suppose you already had 30 cumulative credit units and 108 cumulative quality points. You complete the seven-unit semester above with 28 quality points. The new cumulative totals are 37 units and 136 points.
The illustrative CGPA is 136 ÷ 37 = 3.6757…, or about 3.68 when rounded to two decimal places. Never simply average two semester GPAs if their credit-unit totals differ.
Common mistakes to avoid
Do not multiply raw percentage scores by credit units; first determine the corresponding official grade point. Do not forget course units. Do not apply a classification band taken from another institution without checking the NOUN rules relevant to your programme.
If the portal CGPA differs from your calculation, inspect missing results, repeat-course treatment and the record of registered units before assuming either calculation is wrong.
Use CGPA as a planning tool
Estimate the grade points needed in future courses, while recognising that a strong result in a high-unit course has a larger effect. Prioritise understanding and consistent assessment preparation over chasing a particular letter grade.
The definitive academic record remains the official university result statement, not an unofficial calculator.
Your practical checklist
- I have the correct credit units for every course.
- I multiplied units by grade points.
- I divided total quality points by total units.
- I verified the applicable university grading rules.
Apply what you learned using the corresponding PsalmEduLabs student tool.
Open PsalmEduLabs study tools →Official sources to check: University policies, dates and assessment instructions can change. Confirm course-specific details in the official NOUN resources.
Prepared by PsalmEduLabs as independent educational guidance. Not issued or endorsed by the National Open University of Nigeria.