If you are new to GantterAI or migrating from Microsoft Project, one of the most important concepts to understand is Manual Scheduling vs Auto Scheduling.
Under File > Settings > General, you'll see a switch that will set new tasks to be manually scheduled:
This setting controls who decides task dates:
You, or
GantterAI’s scheduling engine (Critical Path / CPM)
Manual Scheduling (You Control the Dates)
Manual Scheduling means you enter the dates and they stay fixed unless you change them. Tasks that are manually scheduled will be marked with a pin icon:
What happens in Manual Scheduling:
You type the Start and Finish dates
GantterAI does not automatically move the task
Changes to predecessor tasks do not affect this task
Dependencies exist visually, but do not drive dates
This is similar to:
Typing fixed dates directly into MS Project tasks
Pinning a task to the calendar
Use Manual Scheduling when:
A date is fixed by contract or regulation
You are creating high-level milestones
You are still roughing out a plan
You do not want tasks to move automatically
Auto Scheduling (GantterAI Controls the Dates)
Auto Scheduling means you define the logic, and GantterAI calculates the dates.
Auto-scheduled tasks are marked with a blue calendar icon with a circle:
What happens in Auto Scheduling:
You define task duration and dependencies
GantterAI calculates Start and Finish dates
If one task changes, connected tasks update automatically
Critical Path, slack, and float are calculated correctly
This is similar to:
Using fully linked, auto-scheduled tasks in MS Project
Use Auto Scheduling when:
Task order matters
You want a realistic, dependency-driven schedule
You are tracking progress
You want accurate Critical Path results
Which Tasks Should Be Manual vs Auto?
A common mistake for new users is setting too many tasks to Manual Scheduling. This prevents the schedule from updating correctly.
Recommended Approach (Especially for MS Project Users)
Manual Scheduling (Use Sparingly):
Project start or end milestones
Contractual deadlines
External review or approval dates
Auto Scheduling (Use by Default):
Most execution tasks
Tasks with predecessors and successors
Work that depends on other work
Best Practice:
Auto schedule most tasks. Use manual scheduling only when a date must not move.
How Does the Scheduling Mode Affect Dependencies?
Action | Manual Scheduling | Auto Scheduling |
Add a dependency | Does not move task | Automatically recalculates dates |
Change a predecessor | No impact | Downstream tasks update |
Change duration | Dates stay fixed | Dates adjust |
Critical Path accuracy | Limited | Fully accurate |
If your dependencies look correct but dates are not moving, the task is usually manually scheduled.