There is no limit for age in IIM Calcutta or for that matter any MBA college.

 Based on your overall academic profile, you will need to score atleast 99.9 percentile to get a call for the next round.

All the best!

Are you talking about Indian Institute of Management, Calcutta? 

And it never matters what engineering field you were in or you have studied. Nor does it actually matter what your age is. 

What matters is your competency, your capabilities to work efficiently as a student then as a manager and your own will to achieve something in life. 

Even if your date of birth is '92, you would definitely have certain work experience that is given due weight in IIMs. Produce your work experience proof, or your pay slips, as  a proof of your work. 

Talk about your projects, your leadership skills, your initiatives that you took during your work tenure, in the interview when asked. 

Or anything significant that you have done in your life so far after graduation to prove your worth. All you need to show in front of the interviewers is your willingness to study, work smartly and be a good learner.

Stay confident and nothing can come your way!! 

All the best!!