Hi Deep,

               First of all i would like to tell you that first choose which NIT are you looking for. If you are looking for the top NIT like NIT tiruchippalli ,NIT warangal ,NIT Surathkal or NIT Rourkela ,then you have to score around 160-190 and thereby getting a rank of around 4000-6000 for streams like metallurgical and materials engg,chemical engineering,bio technology etc.But for getting better streams like the CSE,ECE,EEE,electrical engg,civil,mechanical then you have to get a rank of around 1000-3000 that is score of around 200+ in jee mains.

You can even get the lower ranked NIT  like  meghalaya,manipur,hamirpur,kurukhetra by getting a score of 130+ for lower streams and 160+ for good streams of engg.

you can also get NIT calicut,silchar,durgapur by getting a score of 150+ for lower streams and 180+ for better streams of engg.Hope this helped you.

Best of luck.