Hello Ajay,

For all NIT's/IIIT's/GFTI's across India, a student must secure a minimum of 75% in their 10+2 or any equivalent examination or should belong to the top 20 percentile in his/her respective state/central board. Whereas for students belonging to the SC/ST category, a minimum of 65% must be secured. 

Since you have secured 7.57 CGPA in intermediate, you can calculate your percentage by multiplying the CGPA to 9.5.

7.57×9.5= 71.9% 

So Ajay your eligibility depends on the category to which you belong to. 

For any further details regarding the eligibility criteria for NIT please refer to the following careers360 link. 

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

For calculating your percentage in intermediate please refer to the CBSE link below.

http://www.icbse.com/cgpa/

Hope this information was helpful.

Thank you.

All the best.