Total float :

• Float is difference between maximum time available and actual time required for the completion of the

  activity. 

• FT = (Maximum available time) – (Actual time required)

• Maximum available time we can get when activity starts at earliest start time and finish by latest finish

   time i.e., 

• Maximum available time = LFT - EST

• Actual time required for performing an activity is the estimated activity time tij

  F_T = LFT - EST – T_ij

F_T=LST- EST

          Or      

F_T=LFT - EFT