IIT Kharagpur has adopted a notional factor of 10 for CGPA to Percent conversion.
This basically means that
Your % = Your C.G.P.A. * 10
Whenever you are required to provide proof of your marks to a company, you can submit your grade sheet. A provisional grade sheet is provided by the institute only on request and after payment of the requisite fee - INR 25
So, your CGPA of 6.5 can be converted into 65 percent.