Business duration is not getting calculated correctly.business rule used for calculation is

[Khushboo8]

if (current.state == 7) {
  // incident state is closed so
  // 1. mark the task as inactive
  // 2. set the closed by to current user if not supplied
  // 3. set the closed time to now if not supplied
  current.active = false;
  if (current.closed_by.nil())
        current.closed_by = gs.getUserID();
  if (current.closed_at.nil())  
        current.closed_at = gs.nowDateTime();

  // now we want to update the fields that indicate the time
  // or duration of this incident from open to close.   We keep
  // track of duration as a glide_duration value (dd hh:mm:ss) and
  // as a pure number of seconds.
  //
  // Both calendar time and business time are maintained

  current.business_duration =
      gs.calDateDiff(
            current.opened_at.getDisplayValue(),
            current.u_resolved.getDisplayValue(),
            false);

  current.business_stc =
      gs.calDateDiff(
            current.opened_at.getDisplayValue(),
            current.u_resolved.getDisplayValue(),
            true);

  current.calendar_duration =
      gs.dateDiff(
            current.opened_at.getDisplayValue(),
            current.u_resolved.getDisplayValue(),
            false);

  current.calendar_stc =
      gs.dateDiff(
            current.opened_at.getDisplayValue(),
            current.u_resolved.getDisplayValue(),
            true);

}

[tarleen]

Please refer to this link for creating schedules -

Using Schedules - ServiceNow Wiki

Please share the respective resolved date , opened date & business duration values which according to you is getting calculated wrongly.

[tarleen]

As already mentioned, Business duration is the time from open to closure, in regards to the primary SLA calendar. So if your Calendar is 8 hour day Mon-Fri, and a incident opens on Mon and closes on   end of Wed, it would display as 1 day (24 hours).

eg :

opened_at : 18/01/2017

resolved_at : 21/01/2017

then the Business duration : 1 day

&                       Duration : 3 days