Project Calendar
Define working days, non-working holidays, and critical milestone dates to ensure accurate timeline calculation in scheduling software.
§1 Purpose of the Project Calendar
The Project Calendar translates raw duration estimates into a realistic timeline by declaring exactly when work can—and cannot—occur.
A schedule built purely on "elapsed days" will invariably fail. Ten days of effort starting on a Thursday will not finish the following Saturday; it will finish nearly two weeks later when accounting for weekends. Furthermore, holidays, firm-wide shutdown periods, and resource-specific non-working days extend durations even further.
The Project Calendar acts as the master foundational setting for scheduling software (like MS Project or Primavera). Before linking any activities, the Project Manager must define this calendar to ensure the software calculates the critical path accurately.
- Working Days: Days where project execution actively occurs (typically Mon-Fri).
- Elapsed Days: Continuous calendar days, including weekends and holidays. Used rarely (e.g., waiting for concrete to cure).
§2 Blank Template
A visual representation format for defining the working parameters of the project timeline.
PROJECT CALENDAR
Working days are [e.g., Monday-Friday] excluding noted holidays. Key project dates and milestones are marked.
§3 Worked Example: Mary's Consulting
A completed example demonstrating the working schedule for an 8-month implementation project, overlaying US federal holidays and major phase gates.
PROJECT CALENDAR
Working days are Monday-Friday excluding U.S. federal holidays. Weekends and holidays are non-working days for the project. Key project dates and milestones are marked.
The Math of Scheduling
Notice that July contains 31 physical days, but only 22 working days due to weekends and the Independence Day holiday. Without this calendar, software would assume 31 days of productive effort.
Visualising Delivery
Highlighting the milestone dates (e.g., Nov 24 Go-Live) alongside non-working days immediately flags risks. A critical milestone set the day after a long holiday weekend requires careful contingency planning.
Resource Specificity
While this is the master project calendar, individual resources (contractors, specific team members) often require their own subsidiary calendars to block out planned annual leave or part-time availability.