Respected sir,

You need to check last years JEE website which gives the cut offs. You can also apply to IIST using JEE Mains and JEE advanced(but you must be prepared to work in ISRO for 3 years(there is a bond) and it is a very uncompromising institution but you will get excellent education there. The JEE advanced is used as a cut off to be allowed to apply and they will use the JEE Mains score for selection.

In IIT's the cutt off is around 2700-2800 for B Tech and around 3000-3500 for Dual degree but varies year to year.

But remember that every year the competition will increase, interests of students vary so you need to do much better than what is predicted

For IIT-B, the cutoffs in the past few years have been in between 1.5k and 2k for Aerospace. The same have been ~2.5k-2.7k for IIT-K, and ~3k for IIT-M and IIT-KGP.

Regarding marks, scoring slightly above 50% of the max marks will surely land you with a rank close to 2k, which is sufficient for getting Aerospace at IIT-K, IIT-KGP, IIT-M but maybe not IIT-B.

Get around 10–15 marks more, and you will nail IIT-B Aerospace.

Still, the best advice (which I received from my tutors) will be to TRY YOUR BEST , and get AS GOOD A RANK AS YOU CAN.

WHAT IF YOU CAN SOMEHOW WORK YOUR WAY INTO TOP 100 AND JUST BECAUSE AEROSPACE CUTOFF IS AROUND 1.5K–2K YOU DO NOT PREPARE TO THE FULL EXTENT?

If you get AIR-1 and then take up Aerospace, you will surely have a THUG LIFE at whichever IIT you go to.

Although on a personal bias, I would go with IIT-K for the world class Aerospace facilities it has (including its own airstrip and huge wind tunnels).

But then, Aerospace Industry is ABSENT in India, unless you find some job as a scientist with ISRO/DRDO or maybe if you happen to become an Aircraft Engineer for some airlines, or you pursue MS/PhD from some top American University in Aerospace, in which case you may even get a chance to go and work with NASA.

P.S. If you do not get that kind of rank in IIT-JEE and end up with something beyond 10k (CLEARING IIT-JEE), DO CONSIDER TAKING AEROSPACE AT IIST, Trivandrum. I wanted to go there but my parents put me here in NSIT, IT.

JEE Advanced maximum marks are not defined :

Maximum Marks vary every year like below:

2016- 372
2015 - 504
2014 - 360

You should score more than 30-40% marks to get good branch in Top IITs