The Project Calendar is a calendar that identifies working days and shifts available for scheduled activities. It defines the timeframes during which project work can be performed, accounting for holidays, weekends, non-working days, and specific resource availability.
The project calendar plays a key role in accurate scheduling, duration estimation, and resource planning.
Key Characteristics
- Defines Work Periods – Specifies allowable working days and hours
- Accounts for Non-Work Time – Includes holidays, weekends, and scheduled breaks
- Supports Resource Planning – Aligns team availability with task scheduling
- Used in Schedule Models – Applied to tasks and resources within project scheduling tools
Example Scenarios
- A global project includes separate calendars for regional teams with different holidays
- Night shift availability is defined for a construction schedule with 24/7 operations
- A project calendar is modified to include blackout periods during system maintenance windows
Role in Project Scheduling
- Enables Accurate Planning – Ensures realistic activity durations and sequencing
- Prevents Conflicts – Avoids scheduling work during unavailable periods
- Aligns with Resource Constraints – Matches tasks to working hours and team capacity
- Improves Forecast Reliability – Supports timeline accuracy by reflecting real-world constraints
See also: Project Schedule, Resource Calendar, Schedule Model, Activity Duration, Work Breakdown Structure (WBS).