How can I calculate my GPA?

Answered

In my country, we use 1-9 grading system. 1 is the best and 9 is the worst grade. This system does relative evaluation.

Grade 1: Top 0-4% (96-100 percentile)

Grade 2: Top 4-11% (89-96 percentile)

Grade 3: Top 11-23% (77-89 percentile)

Grade 4: Top 23-40% (60-77 percentile)

...

I only get grades, not exact percentile or rank. How can I choose the GPA scale in Common App? And how do I count it when I calculate the GPA?

And additionally, there are some subjects that have different grading. They have 3 grades, A, B, and C.

Grade A: 80-100 (Combined score of exams, assignments, performance assessments)

Grade B: 60-80

Grade C: 0-60

There is the students share of each grades in my transcript. Grade A share varies from 10% to 30%. The others goes roughly same. How do I have to count it in GPA?

Lastly, we have primary school, middle school, and high school. I graduated the middle school when I was 15, 9th grade. And 10th grade is when most students enter high schools.

However, my middle school transcript doesn't provide credits, although my high school one does.

How should I adjust them to get cumulative GPA?

Thank for you attentions.