Hi

To be eligible for IITs one needs at least 75% marks in class 12th if belongs to General or OBC category  or at least 65% marks in class 12th if belongs to Sc or St category. For this year i. e 2021 this minimum percentage requirement of 75% - 65 % has been lifted off.

You can check detailed eligibility at

https://engineering.careers360.com/articles/jee-advanced-eligibility-criteria

Admission in IITs is solely on the basis of the rank  obtained by you in JEE advanced examination

If I tell you about rank required for IIT Madras then,

In round 6 of josaa counselling 2020 , for general category closing rank for gender neutral was 7929 rank in jee advanced for Indian Institute of Technology Madras and it was for Naval Architecture and Ocean Engineering (4 Years, Bachelor of Technology)

You can check the same at

https://josaa.nic.in/Result/Result/currentorcr.aspx

So , you should target at least around 7500 rank in jee advanced to be on the safer sideside for IIT Madras

To have a personalised report on your chances of getting a college you can go through our college predictor, it will give you complete list of colleges which you can get on the basis of the category you belong to, your gender etc, the link for  jee college predictor is provided below

Jee main college predictor :-

https://engineering.careers360.com/jee-main-college-predictor?icn=QnA&ici=qna_answer

Jee advanced college predictor :-

Thank you