There is no universal formula for converting your percentage to CGPA or vice versa, and it is also dependent on where you intend to use it.
If you want to apply for graduate studies (assuming you do), your alumni who have applied recently can help you. Contact them through LinkedIn. Seek assistance from your professors/college administration as well, as they may have witnessed/aided other students who have faced similar issues in the past.
Otherwise, if you're just curious about your percentage's equivalent GPA, see if your college, VTU has an established conversion formula for students who want to pursue higher education and must include an equivalent GPA in their applications.
One of my cousins graduated from VTU. According to him this is the procedure to compute the Semester Grade Point Average (SGPA) and Cumulative Grade Point Average (CGPA):
This is how CGPA is CGPA calculated for Visvesvaraya Technical University (VTU) Karnataka from a given percentage.