Hi

Admission in IITs is through  marks or rank obtained by you in JEE advanced examination so JEE advanced is the entrance examination  to get into IITs.

Now to be eligible for JEE advanced examination one needs to first qualify JEE Mains examination so you need to qualify both JEE mains and advanced if you want to get into IITs

Also , to be eligible for  IITs one needs at least  75% marks in  class 12 if belong to general or obc category or at least  65% marks if belongs to SC/ST or  must be in the top 20 percentile in  class 12 examination.

5 Subjects to be considered for calculating percentage are :-

• Physics
• Chemistry
• Mathematics
• A language
• Any subject other than listed above

Thank you