Step duration is the time interval from step start to finish. Duration can be set in the Process Builder (in the Steps tree or step properties) or in the Gantt chart (by clicking proper step duration and editing). This property is used to pre-calculate other steps dates and suggest a timeline for process (especially in duration-driven calculation mode of steps).

Duration can be set as static value (in days, hours and minutes) or as an expression (formula) which should return a result as a number of days/hours/minutes. To set a duration in the Gantt Chart just click on it and type a new value or formula (1):

Setting step duration causes change of step dates (start or end, depending on selected Recalculation Algorithm). The resulting dates depend on Business Hours in the current organization.

Steps have no dates by default - they are driven by durations.

When user comes to Gantt chart, he can see Planned dates that are suggested by system. System will offer Planned Dates for steps beginning from the current system date ("today") which is assigned as Planned Start Date for first step(s). User can accept suggested dates or change them (2) and save Gantt - after this Planned Dates will be stored for steps in the proper process instance. In this case Planned dates will be available next time user opens Gantt and will be shown on Process Progress bar information tooltips.

If user do not save Gantt, planned dates will not be saved and will be offered based on current day each time user opens Gantt chart again.

Planned dates can be changed only if there are no Actual dates for proper step stat or finish. This means user can set new Start/End Planned date if step has no Actual Start/End Date (3), but if step has a Due Date, Planned End Date still can be changed (4).

Forecasted dates (5, light gray) are virtual and are used in Gantt charts only to show future steps supposed dates and position. They are not used anywhere else.

Actual Dates (6) are the real dates when step has been started (Actual Start Date) or completed (Actual End Date). They are shown on Process Progress Bar too, and can't be changed.

Due Date (7) is similar to Forecasted End Date. It is suggested by system for steps that have an Actual Start Date, but still have not Actual End Date (Active and Pending steps). Due Date is calculated by adding step duration to Actual Start Date.