Hi,

Aspirants can get lower branches in NITs through home state quota. Though students get admission through their rank irrespective of the marks he or she obtains in JEE Main. If you belong to a reserved category you can easily get your preferred branch in any NITs through home state quota.

Suggestion: DON'T THINK ABOUT HOW MUCH MARKS YOU CAN ACHIEVE. THINK ABOUT HOW GOOD YOU CAN PERFORM. Remember those words from Rancho, " Success ke pichhe mat vago, excellence ke pichhe vago, success apne ap aa jayega."

All the best !

If you meant 30 percentile, irrespective of your Category, a seat in NIT is not possible. Going by previous years trends, you will need atleast a percentile of 90 and above for a seat in any NIT.  Your All India Rank is calculated by the formula 100-your percentile*869010/100. With a percentile of 30, you may have to reappear for JEE Mains September session. 30 percentile, truth be told is very less even with reservations.