Resource calendars
A resource calendar shows when specific people, equipment, or facilities are available or unavailable for project work. It lists working time, non-working time, shifts, and other constraints that affect scheduling and assignments.
Key Points
- Lists availability and non-working time for people, equipment, and facilities.
- Includes working days, shifts, holidays, time-off, and time-zone or location details.
- Used to estimate durations, assign resources, and validate schedule feasibility.
- Highlights resource conflicts and supports resource leveling and smoothing.
- Maintained collaboratively by the project manager, resource managers, and often PMO or HR.
- Typically implemented in scheduling tools and linked to enterprise or organizational calendars.
Purpose
Ensure that activities are planned and assigned only when required resources are actually available. Resource calendars reduce scheduling conflicts, support realistic duration estimates, and enable effective allocation of people and critical assets.
Source & Ownership
- Primary sources: HR systems, PMO standards, functional managers, and enterprise calendars.
- Ownership: The project manager uses it for planning; functional/resource managers provide and approve availability data.
- Updates: Adjusted as team members join/leave, shifts change, or new constraints (training, maintenance) arise.
- Tooling: Commonly maintained in PPM or scheduling tools (e.g., resource pools, team calendars) integrated with corporate calendars.
How to Use
- Collect base calendars: organization-wide working days, holidays, and standard shifts.
- Add resource-specific details: individual time-off, training, part-time status, locations, and time zones.
- Record equipment/facility windows: maintenance shutdowns, booking rules, and capacity limits.
- Link the calendars to activities in the schedule so estimates reflect real availability.
- Run resource analysis (leveling/smoothing) to resolve over-allocations or gaps.
- Review and update regularly; communicate changes to the team and stakeholders.
Example Usage
During schedule development, the project manager sees that two key analysts are on leave the first week of July. The team defers a requirements workshop to the following week and assigns preparatory tasks to available staff. For testing, the lab calendar shows one test rig down for maintenance, so the plan staggers test execution to avoid idle time.
Caveats
- Outdated calendars lead to unrealistic dates and resource conflicts.
- Respect privacy: store only necessary availability details, not sensitive personal data.
- Consider time-zone and location differences when planning cross-regional work.
- Contractor availability may change quickly; confirm frequently and include contingency.
- Do not assume full-day availability; account for partial allocations and shared roles.
PMP Example Question
While finalizing the schedule, the project manager needs to verify whether a specialized technician can support an activity next month. Which document should the manager consult first?
- Resource calendars
- Risk register
- RACI matrix
- Work performance data
Correct Answer: A — Resource calendars
Explanation: Resource calendars show individual and asset availability and constraints. They are the primary input to confirm whether a specific resource can be assigned at a given time.
