Dear Aspirant,
Getting admission in an National Institute of Technology depends upon certain factors such as your desired NIT, your state, your category and sub category, your gender and the branch of your interest. Assuming you do not have any of these factors in favour of you, you will need a minimum of 99 percentile, however, with one or more of these factors in consideration you can get into nit at 90 percentile too.
Here is a list of previous year cutoff for NITs:-
https://engineering.careers360.com/articles/jee-main-cutoff-for-top-nits
Regular exam updates, QnA, Predictors, College Applications & E-books now on your Mobile