Semester GPA versus cumulative GPA: credits change the answer
A four-credit course counts twice as much as a two-credit course in a credit-weighted GPA. That is why adding the grade values and dividing by the number of courses can produce the wrong answer.
What the weight does
Multiply each course’s grade points by its included credits, add those products and divide by the included credits. Georgia Tech’s registrar describes this mechanism, but your institution determines its own scale and exclusions.
References: Georgia Tech Registrar — Grade Point Average Calculation
Semester and cumulative averages answer different questions
A semester GPA covers the included courses in one term. A cumulative GPA combines the points and credits across terms. Averaging two semester GPAs directly is only valid when their weights are equal.
To combine previous study with new grades, you need both the earlier GPA and its credits. If an official total of quality points is available, use it: the displayed GPA may already have been rounded.
What a general calculator cannot decide
Repeated courses, pass/fail subjects, transfer credits and incomplete grades depend on academic rules. They are not merely rounding choices.
- Keep one grading scale throughout; do not mix points on a 4-point and a 5-point scale.
- Use credits included in the GPA, which may differ from all enrolled credits.
- Treat a planning result as an estimate. Use the official transcript and regulations for formal decisions.
An original two-course example
One course has 3 credits at 4 points, another 2 credits at 2 points. Weighted points total 3 × 4 + 2 × 2 = 16. The semester GPA is 16 ÷ 5 = 3.2.
If the earlier record contains 30 credits at an unrounded GPA of 3.0, the combined result is (30 × 3 + 16) ÷ 35 = 3.028571…, approximately 3.03 rounded to two places. Simply averaging 3.0 and 3.2 gives 3.1, which is wrong for these unequal credit totals.