Hi i need to calculate the time between Login and Logout in asp.net using c#

Check out the attachment contains simple login as well logout with conting the time in seconds.

You can do like

While login get the current time like bellow
 DateTime _starttime = DateTime.Now;//keep this time in session variable
Sessio["Start"]=_starttime;

Next when user log out
TimeSpan ts;
DateTime _starttime=Convert.ToDateTime(Sessio["Start"]);
ts = DateTime.Now.Subtract(_starttime);
double _ttaken = ts.TotalSeconds;//here u can get minutes,hours,seconds,days