A project calendars template defines the working days, non-working days, shifts, and resource availability windows used as inputs to schedule development and resource planning. According to the Project Management Institute (PMI), the project calendars template supports the Planning Performance Domain in PMBOK 8 by ensuring schedules reflect realistic working patterns for the team and resources involved. Schedules built without accurate calendar inputs routinely miss deadlines because they assume resources are available when they are actually on leave, celebrating local holidays, or assigned to other projects. The project calendars template prevents these avoidable schedule failures by capturing all non-working time upfront before the schedule network is built and durations are calculated using calendar-adjusted workday counts.

What is a Project Calendar?

A project calendars template is a document that identifies the available working days and hours for the project and its resources. It captures standard work hours, public holidays, planned leave periods, regional working pattern differences for global teams, and resource-specific availability constraints — all of which are inputs to schedule network analysis, resource leveling, and duration estimation. The project calendars template is distinct from the resource calendars template in that it defines the baseline working pattern for the project as a whole, while resource calendars document individual variations from that baseline. In PMBOK 8, accurate project calendars are a prerequisite for reliable schedule development, as all duration calculations, network analysis, and critical path identification depend on knowing which days are available for work. Errors in calendar setup propagate through the entire schedule and undermine earned value calculations that compare planned to actual performance.

What's Included in This Project Calendars Template?

• Project Calendar Sheet — Month-by-month visual view of working and non-working days for the full project duration, color-coded to distinguish standard working days, weekends, public holidays, organizational shutdowns, and project-specific non-working periods.
• Holiday and Non-Working Day Register — Comprehensive list of all official public holidays, organizational holidays, planned team events, and other non-working periods, organized by country or region for geographically distributed teams working across multiple jurisdictions.
• Resource Calendar Summary — Aggregated view of availability percentages and key constraints for each team member, enabling the project manager to identify periods of reduced team capacity that need to be reflected in the project schedule.
• Shift and Work Hour Definitions — Standard daily work hours, overtime rules, maximum working day definitions, and shift pattern specifications for projects with shift-based work schedules or regulatory constraints on maximum working hours.
• Calendar Assumptions and Basis — The regional, contractual, and organizational basis for all calendar settings, documenting which collective agreements, employment contracts, and organizational policies were used to define the working pattern.

How to Use This Project Calendars Template (PMBOK 8)

1. Establish during the Develop Schedule process — Create the project calendars template before building the schedule network. Schedule software (MS Project, Primavera, etc.) requires calendar input to calculate activity durations in calendar-adjusted workdays rather than raw elapsed time.
2. Collect holiday information from all team locations — For geographically distributed teams, gather the official holiday calendars for every location where team members are based. Failing to account for regional holidays is a common cause of missed deadlines in global projects.
3. Create individual resource calendars for non-standard availability — Use the resource calendars template to document planned leave, part-time availability, and competing project commitments for each team member on top of the project calendar baseline.
4. Import or reference calendar data in your scheduling tool — Ensure the project calendars template is reflected in whatever scheduling tool the team uses, whether MS Project, Primavera, Jira, or another platform. Manual schedule calculations without calendar adjustment are inaccurate.
5. Update when team composition or project location changes — If team members join from new locations or the project work moves to new sites during execution, update the project calendars template to reflect the new working patterns and recalculate affected schedule activities.

When to Create This Document (PMBOK 8)

The project calendars template is created during the Planning Performance Domain, before schedule development begins. In PMBOK 8, calendars are a required input to the Develop Schedule process and must be established before any network analysis or duration calculation can produce reliable results. The calendars are updated during execution when team changes, site changes, or unexpected non-working periods require schedule recalculation.

Related Templates

• Schedule Management Plan Template
• Resource Calendars Template
• Schedule Data Template
• Project Team Assignments Template
• Resource Requirements Template