hi surya,

There are 3 kinds of NITs:

Top NITs like NIT trichy, Warangal, Rourkela, allahabad etc : To get into these NITs you need a rank under 30k.

Mid tier NITs like NIT Jalandhar , Hamirpur, Jamshedpur etc :  To get into these NITs you need a rank under 40k.

Lower NITs like NIT Sikkim, Puducherry etc : To get into these NITs you need a rank under 42k-43k.

These are cutoffs for other state, if you have home state quota you can get a NIT seat at 60k-70k depending on the competition on your state. I will advise you try to get a rank under 25k.

I hope this answer will help.
All the best for the future!!