Hi Renjith,
As Guy Rosenthal suggested "TruClient footprint depends on several parameters (AUT, HW, OS, Browser version) and can vary immensely."
You should make the calculations in your environment with the script you are planning to test. Please find additional information and links to knowledge documents which explain how to make these calculations in the following post: http://h30499.www3.hp.com/t5/LoadRunner-Support-Customer/LoadRunner-Support-Tip-How-to-calculate-the-load-generators/td-p/6358699
Kind regards,