Hello,

Admission in NITs, IITs or GFTIs is only possible through JEE MAINS and the minimum percentage that makes a candidate eligible to appear for JEE MAINS is 75 percent for General and 65 percent fir reserved candidates such as SC/ST (however, for the year 2021-22 this criteria will not applicable and there is no such a minimum percentage required but maybe IITs will not consider you with low marks). Have a look at the detailed eligibility criterias to sit in the JEE MAINS-

1. Candidates should have passed in the year 2019,2020 or appearing for 2021, candidates with the passing year of 2018 and before are  not eligible.

2. Candidates will get 3 attempts for JEE MAINS and 2 attempts for JEE ADVANCED.

Reservation in JEE MAINS

OBC NCL- 27 percent

SC- 15 percent

ST- 7.5 percent

EWS- 10 percent

PWD- 5 percent.

JEE MAINS was previously conducted by CBSE, and it is conducted by NTA (National Testing Agency). It held four times in a year in the month of March, April, May and June. For more information please go through this link

https://www.google.com/amp/s/engineering.careers360.com/articles/jee-main-eligibility-criteria/amp

Good Luck.