B.Tech admission at IITs is done through online counseling conducted by JOSSA on the basis of marks obtained in JEE Advance. So the criteria is same for IIT Kharagpur also.

Eligibility

As per the eligibility criteria to apply for JEE Advance you should have minimum 75% as a general category in 10+2 board or you should be in top 20 percentile in class 12th.

To check complete information you can go through with given below link.

JEE Advance Eligibility