Is percentile calculation category based?Meaning is percentile calculated separate for each category

Hello.
If you are talking for JEE mains percentile then there are two type of percentile one is your subject wise percentile and other is your overall percentile and if talking about rank then there will be two type of rank one is your GENERAL rank i.e, AIR and other is your category wise rank. And remember there is not any percentile which is different for different category candidate but yes rank is different ,  everyone also have a common rank which is your AIR.
Best of luck.