Hi Milan,
Top 20 percentile is calculated by taking into account FIVE subjects-
The total marks are calculated out of 500 marks which you obtain in the FIVE subjects mentioned above and then a list of Top 20 percentile is prepared by your respective Board and sent to JoSSA which releases the list of all the Boards.
Now, you need to understand that the Top 20 percentile is different for different boards and different categories.
For example, CBSE has a different cutoff for OBC category and Maharashtra HSC has a different cutoff for the same category.
Therefore, you need to provide me your category and your Board from which you gave the 12th examination, then only I can tell whether you are in the Top 20 percentile or not.
Hope this helps you.
All the best!!!
Regular exam updates, QnA, Predictors, College Applications & E-books now on your Mobile