The cutoff for different colleges and branches are different each year.You have not mentioned that under which exam and institutes or branches you are asking.I assume that you are asking for JEE MAIN exam.So,the answer is that you can not actually calculate the cutoff for any branch, institute,exam etc.You can only predict on the basis of previous year trends and cut off.The cut off changes every year based on the demand of a particular Branch of a particular Institute and also the Rank of applicants to that particular college.Generally CSE has a higher cut off due to high demand of CSE.But,if this demand will go down someday in future then the cut off will come down automatically.So,there is no formulae to calculate cut off.It depends on various factors.
Hope i am clear to you.

Hi Kaviya,

These cutoff for JEE mains, Mhtcet, Bits Pilani, these are all based on the nom of students applying for the exam, no. Of seats available, and the difficulty level of the paper. It's for sure that if the paper will be easy, the cutoff will be high, and vice versa. The cutoff will enclose to the previous years cutoff. You just need to focus on the studies and subjects. Distribution of marks will always be equal. Coaching institutes give their approximate cutoff every year. The cutoff are always governed by their conducting body. Previous year cutoff might help you.

All the best and do ask for any further queries.