Duration

What "Duration" means

• definition: Duration is the number of working days a task spans. We schedule on business days/hours only.
• units: Durations are whole numbers in days. Entering 1, 5, 10, etc. sets 1/5/10 working days.
• milestones: A milestone has a duration of 0 and starts and finishes on the same business day (08:00–17:00).
• minimum: Non-milestone tasks must have a duration of at least 1 day. Zero-duration is only allowed for milestones.

How duration is used in scheduling

• auto-finish from start + duration: When you change a task's duration and it has a start date, the finish is recalculated using business-day math.
• auto-finish from start edits: When you change a task's start and it has a duration, we recompute the finish accordingly.
• duration = 1 means same day: A 1-day task starts at 08:00 and finishes at 17:00 on the same business day.
• defaults:
  • New tasks default to 1 day duration (or 0 if marked as a milestone).
  • If you provide both start and finish but no duration, we infer duration as the inclusive business-day count between those dates (minimum 1, unless milestone).

Business day rules

• Working hours: Tasks start at 08:00 and finish at 17:00 local business time.
• Time normalization: All start times are normalized to 08:00, and all finish times to 17:00.
• Weekend skipping: Weekends (Saturday and Sunday) are automatically skipped when computing start/finish dates.
• Business day alignment: If you enter a date on a weekend, it will be adjusted to the nearest business day (forward for starts, backward for finishes).

Predecessor constraints

• editing allowed: You can edit duration, start, and finish dates even when tasks have predecessors.
• FS enforcement: When a task has Finish-to-Start predecessors, its start date is constrained to the next business day at 08:00 after the latest predecessor finishes.
• Automatic clamping: If you manually enter a start date earlier than the constraint, it will be automatically clamped to the constraint.
• Finish edits: When you edit finish for a task with predecessors, your finish date is preserved and duration is recalculated from the constrained start to your finish date.
• Duration edits: When you edit duration, finish is recalculated from the constrained start + duration.
• Cascading: Changes to a predecessor's dates cascade through all dependent tasks.

Milestone behavior

• Duration forced to 0: Milestones always have a duration of 0, regardless of what you enter.
• Same-day times: Milestones start at 08:00 and finish at 17:00 on the same business day.
• Date normalization: If you enter different start/finish dates for a milestone, both will be normalized to the same business day.

Editing duration in the UI

• In the Plan grid, type a whole number in the Duration column. This value is interpreted as days.
• In the Gantt editor dialog, the field is labeled "Duration (days)" and accepts only numeric values.
• Resizing a bar in the Gantt also adjusts the task's duration based on the inclusive day span.

How to enter duration

• Enter whole numbers (1, 5, 10, etc.) directly in the Duration column - these represent working days
• For multi-week tasks, calculate the working days (e.g., 2 weeks = 10 working days)
• Duration 1 = same day (start 08:00, finish 17:00)
• Duration 5 = one work week (Mon 08:00 to Fri 17:00)

Validation errors

The system will flag the following errors:

• Zero duration on non-milestones: Non-milestone tasks must have duration ≥ 1
• Finish before start: The finish date cannot be before the start date
• Self-predecessor: A task cannot be its own predecessor
• Circular dependencies: Tasks cannot form a dependency cycle (e.g., Task A → Task B → Task A)

Examples

Example 1: Simple 1-day task

• Duration: 1
• Start: 2025-01-13T08:00 (Monday)
• Finish: 2025-01-13T17:00 (same Monday)

Example 2: 5-day task spanning a week

• Duration: 5
• Start: 2025-01-13T08:00 (Monday)
• Finish: 2025-01-17T17:00 (Friday)

Example 3: Task spanning weekend

• Duration: 2
• Start: 2025-01-17T08:00 (Friday)
• Finish: 2025-01-20T17:00 (Monday, weekend skipped)

Example 4: Task with predecessor

• Task 1 finishes: 2025-01-15T17:00 (Wednesday)
• Task 2 (successor) starts: 2025-01-16T08:00 (Thursday, next business day)

Example 5: Milestone

• Duration: 0 (forced)
• Start: 2025-01-15T08:00
• Finish: 2025-01-15T17:00 (same day)

Tips

• Prefer changing duration in the Duration column rather than forcing dates via Start/Finish, especially for linked tasks, to avoid conflicts with dependencies and constraints.
• For tasks with predecessors, you can edit duration, start, or finish. The system will automatically enforce constraints:
  • Start dates are clamped to respect predecessor constraints.
  • Finish edits preserve your finish date and recalculate duration.
  • Duration edits recalculate finish from the constrained start.
• Use milestones to mark key project events or deliverables with zero duration.
• For multi-week tasks, convert to days (e.g., 2 weeks ≈ 10 working days) given your team's working calendar.

FAQ

Can I enter partial days or hours?

Not at the moment. Only whole-day durations are supported.

Why did my finish date move to 5:00 PM?

We normalize finishes to the end of the business day (5:00 PM) to keep schedules consistent.

How is project duration computed?

Project duration is derived from the schedule across all tasks (including predecessors) and can be reviewed via the project/summary tasks; it reflects the business-day span of the plan.

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Last updated: 2025‑01‑31