GPA and CGPA both summarize grades, but they often describe different periods. A semester GPA covers one term, while a cumulative GPA combines several terms.
Why credits still matter
Do not simply average semester GPAs when the semesters contain different credit totals. Multiply each semester GPA by its credits before combining them.
A short example
A 3.2 GPA over 15 credits and a 3.6 GPA over 18 credits combine to about 3.42. Compare the GPA Calculator with the CGPA Calculator.