Hello aspirant,

In order to get admission in IIT Bombay, you have to clear the JEE mains examination first and then the JEE advance exam. You have to clear the required JEE mains Cutoff for the respective category in JEE mains to eligible in JEE advance. Then in JEE advance you have to clear the cutoff for getting admission in core branches in IIT bombay. The candidates must have secured at least 75% marks or be in the top 20 percentile in the 12th Class Examination conducted by respective boards. For SC/ST students, there shall be a relaxation of 5% in this criterion.

Since you have not mentioned your category I am considering you as a General category student. Now, for general category student, in order to get decent branches like Aerospace, chemical, civil, mechanical, you have to score at least within 500-2000 rank in JEE advance. But for core branches like CSE you have to score within 100 rank in JEE advance.

further, to know more about the Cutoff required in JEE advance for IIT Bombay, you can follow the below mentioned link to know more : https://engineering.careers360.com/articles/jee-advanced-cutoff-for-iit-bombay

I hope that this will help.