Hello Minati ;

For starters believing in yourself during the exam is the most important criteria that you need to setup for yourself.

I understand your concern but this is a common thought in a JEE main preparing candidate; thinking how much should he score to get a better rank. A mark that he should Target on achieving.

But I'd suggest you to believe in your preparation first. You can always score good marks in JEE main if you know how to manage time and have studied completely without ignoring any chapters.

Speaking about marks to score to get more than 99+ Percentile ; it might vary from shift to shift. And the toughness of paper might vary also from last year. But assuming the toughness of papers from last year I'd like to suggest how much to score out of 300.

Starting from this year NTA is conducting JEE mains in a total of 300 marks. You can always score good marks without consuming any time in chemistry. So, it's very important not just to do good but to do it faster while doing chemistry paper. Getting 80+ in chemistry will be preferable.

Speaking of maths it'll consume time but you can score 70+ here also if you do good. For physics the answer is same as that for mathematics. In one shift math paper might be lengthy while in another physics will be lengthy. So, considering that you have to score 140+ in both of these papers.

As a total getting 220+ surely can get you a rank under 10,000.

Hope my answer helps you in your preparation!