Duration for tasks can be calculated or entered. Application calculates the duration of a task by counting the amount of active working time between the scheduled start and end of the task. This is generally the time from task start to finish, not counting nonworking time.
Tip: Enter the duration for tasks when you create the tasks. The Duration field is one of the major elements for scheduling calculations. It is the span of time shown by the Gantt bars on the Gantt Chart.