Question

how to calculate cgpa

Answer 1

First, Add grade points that you got in each subject.
Then divide it by the number of subjects.
That is your CGPA.

For example:
Let's say there are five subjects. 
Grade points for 5 subjects are:
Subject 1: 7,
subject 2: 8,
subject 3: 9,
subject 4: 9,
subject 5: 6

Add them: 7+8+9+9+6= 39
Divide the sum by 5 i.e. 39/5 = 7.8
Therefore, Overall CGPA is 7.8

Answer 2

First know your grade points in each subject.Then add them all.After doing the addition, divide the sum by the number of subjects you are having. This is your CGPA.