How CGPA is calculated
Your CGPA summarises your academic performance in a single number. Understanding how it is built — from each course grade, weighted by credit units — helps you set realistic targets and spot mistakes when a figure looks wrong. This guide explains the method step by step.
GPA vs CGPA
GPA (Grade Point Average) measures your performance in a single semester. CGPA (Cumulative Grade Point Average) combines every completed semester into one running average. In other words, your CGPA is the weighted average of all your courses so far, while GPA is the weighted average of one semester's courses.
The weighted formula
Each course contributes a number of quality points — its grade point multiplied by its credit units. GPA is the total quality points divided by the total credit units:
GPA = Σ(grade point × credit units) ÷ Σ(credit units)CGPA uses the same idea across everything completed so far:
CGPA = Σ(all quality points to date) ÷ Σ(all credit units to date)A practical shortcut for cumulative figures: your previous quality points equal your previous CGPA multiplied by your previous total credit units. Add the new semester's quality points and units, then divide.
A worked example
Example — on a 5.0 scale (A=5, B=4, C=3, D=2, E=1, F=0)
A semester with four courses: A (3 units), B (2 units), C (4 units), A (1 unit).
Quality points = (5×3) + (4×2) + (3×4) + (5×1) = 15 + 8 + 12 + 5 = 40.
Total credit units = 3 + 2 + 4 + 1 = 10.
Semester GPA = 40 ÷ 10 = 4.00.
Now suppose you had previously completed 40 units at a CGPA of 3.50. Previous quality points = 3.50 × 40 = 140. Combined with this semester: total quality points = 140 + 40 = 180, total units = 40 + 10 = 50. New CGPA = 180 ÷ 50 = 3.60.
You can reproduce this exactly in the CGPA Calculator.
What credit units mean
Credit units show how much a course "weighs". A 4-unit course affects your GPA roughly four times as much as a 1-unit course with the same grade. That is why a strong grade in a heavy course lifts your average more than the same grade in a light one — and why weighting by units matters.
Institutional grading differences
Grade points and the boundaries for each grade are not identical across every Nigerian institution, and they can change over time. Many universities use a 5.0 scale, while some programmes use a 4.0 scale; the mark ranges that earn an A, B, C and so on also vary. Always confirm the exact scale and class-of-degree boundaries in your own institution's handbook. Any example on this page is an illustration on a stated scale, not a universal standard.
Common calculation mistakes
- Not weighting by credit units. Averaging grade points directly ignores how heavy each course is.
- Mixing scales. Using 5.0 grade points with 4.0 assumptions (or vice versa).
- Dropping failed-course units. A failed course usually still counts its units with a grade point of 0 — check your school's rule.
- Rounding too early. Round only the final figure, not each step.
- Wrong previous totals. For a cumulative figure, use your correct previous CGPA and previous total units.
FAQ
Does a failed course count?
In most systems a failed course still contributes its credit units with a grade point of 0, which pulls your average down until it is repeated and replaced according to your school's policy. Confirm the exact rule at your institution.
Can my CGPA recover after a bad semester?
Yes. Because CGPA is a weighted average over all units, stronger later semesters raise it — the more units you complete well, the more a single weak semester is diluted.
Why is the calculator's result different from my manual estimate?
The most common reasons are forgetting to weight by units, mixing scales, or entering the wrong previous totals. Re-check each course's units and grade.
Try it with your own courses
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Open the CGPA Calculator