Skip to content
Kairos OneBook a demo
Menu
Foundation · 2 min read

Build and audit P6 calendars

Create project calendars, define shifts and exceptions, assign them deliberately, and verify their effect on dates and durations.

Working definition

Calendars are calculation inputs. A five-day calendar, six-day calendar, night shift, shutdown calendar, and procurement calendar can produce different dates from the same numeric duration. P6 also converts between hours and displayed days using administrative time-period settings, so professional reviewers inspect both the calendar and the units used to communicate duration.

Version scope

Desktop P6 Professional workflow. Menu labels are aligned with Oracle’s current Version 26 help; older 24.x deployments may show minor wording or privilege differences.

Key takeaways

  • A calendar changes dates, float, and duration interpretation.
  • Project calendars reduce unintended cross-project impact compared with casually editing shared global calendars.
  • Verify both calendar definitions and activity/resource assignments.
01

Global, project, and resource calendars

Global calendars can be used across projects, project calendars travel with a project, and resource calendars can govern resource-dependent work. Choose the narrowest appropriate scope. Editing a shared global calendar may change dates in projects the editor did not intend to touch.

02

Audit exceptions and assignments

Review working days, shifts, holidays, weather assumptions, possession windows, and special exceptions. Then run a calendar-assignment report: a correct calendar that is not assigned does not affect the schedule.

Create a project calendar without changing unrelated projects

Copy an approved calendar, edit the project copy, and verify assignments before scheduling.

Menu path: Enterprise > Calendars > Project

Before you start

  • Approved workweek and shift plan
  • Holiday and shutdown list
  • Defined hours-per-day reporting convention

  1. Open project calendars

    Choose Enterprise > Calendars, select Project, and confirm the target project.

    Verify: The dialog identifies the intended project calendar scope.

  2. Copy an approved base

    Click Add, select the closest governed calendar, and give the new calendar a descriptive name.

    Verify: The new calendar is project-specific and clearly identifies shift or work pattern.

  3. Modify work periods

    Click Modify and define regular work hours, nonwork days, holidays, shutdowns, and approved exceptions.

    Verify: Spot checks across several months match the source calendar register.

  4. Assign intentionally

    Assign the calendar to the applicable activities and verify the project default for new activities.

    Verify: A calendar-assignment column or report shows the intended population.

  5. Schedule and inspect

    Run F9 with a saved log, then inspect changed dates, float, and paths.

    Verify: Changes are explainable from the calendar difference and no unrelated project changed.

    Field-ready control

    Calendar control check

    • Calendar scope is correct.
    • Workweek and shifts match the plan.
    • Holidays and exceptions are complete.
    • Hours-per-period convention is documented.
    • Activity assignments are reviewed.
    • Date and float effects are checked after scheduling.

    Common questions

    Why can two activities with the same duration finish on different dates?

    Their calendars, start times, exceptions, resource dependence, or scheduling conditions may differ. Compare the assigned calendar and work hours before assuming an error.

    Sources and scope

    Follow the reference trail.

    This guide is original educational commentary. Kairos reference records identify the source organizations, editions and scope behind this guidance. The original publishers retain their publications and rights.

    Create a project calendarOracle · checked 2026-08-01Primavera P6 Professional User Guide, Version 26Oracle · checked 2026-08-01Schedule Assessment Guide: Best Practices for Project SchedulesU.S. Government Accountability Office · checked 2026-08-01