GPA and CGPA: The Difference
GPA is your Grade Point Average for a single semester. CGPA is your Cumulative Grade Point Average, which combines every semester you have completed. Your final CGPA decides your degree class, so it is worth understanding early.
Both are weighted by credit units. A 4-unit course matters more than a 1-unit course. That is why you cannot just average your letter grades.
The 5.0 Scale and Grade Points
Many Nigerian universities use a 5-point system. A common version is:
| Grade | Typical score range | Grade point |
|---|---|---|
| A | 70 to 100 | 5 |
| B | 60 to 69 | 4 |
| C | 50 to 59 | 3 |
| D | 45 to 49 | 2 |
| E | 40 to 44 | 1 |
| F | 0 to 39 | 0 |
Score ranges can differ by school, and some schools drop grade E. Always follow the scheme in your own handbook.
CGPA = total quality points / total credit unitsQuality points for a course = credit units x grade point. Add quality points and units across all semesters before dividingWorked Example: One Semester
Take a first semester with six courses.
- Quality points for each: 3 x 4 = 12
- 2 x 5 = 10
- 3 x 3 = 9
- 2 x 2 = 4
- 3 x 5 = 15
- 2 x 1 = 2
- Sum of quality points = 52 and total units = 15
- GPA = 52 / 15
Worked Example: Moving to CGPA
Now add a second semester with 16 units. Suppose its total quality points come to 66 (so its GPA is 66 / 16 = 4.13). Notice you cannot get CGPA by averaging 3.47 and 4.13 blindly, because the semesters have different units.
- Add the quality points: 52 + 66 = 118
- Add the units: 15 + 16 = 31
- Divide: 118 / 31
The simple average of 3.47 and 4.13 is 3.80. It happens to be close here, but with a big difference in units the two methods can differ a lot. Use the weighted method every time.
What Your CGPA Means
Degree classes depend on CGPA ranges, and these vary slightly by university. A widely used 5.0 scheme is:
- First Class: 4.50 to 5.00
- Second Class Upper: 3.50 to 4.49
- Second Class Lower: 2.40 to 3.49
- Third Class: 1.50 to 2.39
Check your school's regulations for the exact ranges, pass rules and what happens below the lower limit.
Projecting Next Semester
You can use the formula to see what is possible. Continue the example: you have 118 quality points over 31 units, and you will take 18 units next semester.
- Quality points for all B: 18 x 4 = 72, so total = 118 + 72 = 190
- Total units = 31 + 18 = 49
- CGPA with all B: 190 / 49 = 3.88
- Quality points for all A: 18 x 5 = 90, so total = 118 + 90 = 208
- CGPA with all A: 208 / 49
This shows how slowly a CGPA moves once you have many units behind you. Even a perfect semester lifted the CGPA from 3.81 to about 4.24, not to 5.0. That is why starting well matters, and why every semester counts.
How to Improve Your CGPA
- Work out the target. Use the projection method to see what grades you need over the remaining units.
- Protect high-unit courses. A 4-unit course affects your result more than a 1-unit course, so give it extra time.
- Fix F grades. An F adds units but zero points. Retaking and passing the course raises your total.
- Do not neglect small courses. A string of D and E grades in 1 or 2-unit courses adds up.
- Use continuous assessment. CA marks are the easiest to secure if you attend and submit on time.
- Practise past questions for each course before the exam.
Common Mistakes
- Averaging semester GPAs instead of using total quality points and total units.
- Using the wrong grade scale, for example a 4.0 scale on a 5.0 school.
- Forgetting to include failed courses in the total units.
- Ignoring the effect of carry-overs when planning your final year.
What to Do Today
- Find your school's grading scale in the handbook
- List all courses so far with units and grades
- Compute total quality points and total units
- Divide to get your current CGPA
- Project next semester with all B and all A to see the range
- Choose two courses where you will focus your extra effort