Calendars in Microsoft Project
Calendars tell Microsoft Project when work can and cannot be scheduled. A base calendar is a template for a project, task, or resource calendar; those calendars can then adjust the template for a particular schedule. This article describes calendar behavior in Project desktop editions.1
The four calendar types
Section titled “The four calendar types”| Calendar | Role |
|---|---|
| Base | Shared template for standard working and nonworking time |
| Project | General working pattern for the project |
| Task | Exception or special schedule for one task |
| Resource | Working pattern for one person or piece of equipment |
A base calendar defines working hours, working days, and exceptions. Project includes Standard, 24 Hours, and Night Shift base calendars by default, and an organization can create others. Project, task, and resource calendars can use a base calendar as their starting point and then adjust it for a specific schedule.1
The base calendar is a template, not a fourth layer that is independently stacked with the project, task, and resource calendars.
How calendars affect dates
Section titled “How calendars affect dates”By default, tasks are scheduled using the project calendar. A task calendar sets the task’s working time and overrides the project calendar for that task. However, an assigned resource’s calendar can still limit scheduling unless Scheduling ignores resource calendars is enabled. That setting can allow work during the resource’s nonworking time, so use it deliberately.
Project accounts for the configured project, task, and resource calendars when it calculates available working time. Their base calendars provide the template; the project, task, or resource calendar can then add exceptions or different working periods. The result can change when a working day becomes nonworking, when a shift changes, or when a resource is unavailable. Think of calendars as schedule inputs rather than labels attached to tasks.
Set the project’s normal work pattern
Section titled “Set the project’s normal work pattern”The project calendar can use an existing base calendar or be customized. In desktop Project, the controls are Project > Change Working Time for work weeks, specific hours, exceptions, and time-bounded schedule periods, and Project > Project Information for selecting the calendar.2
Use the project calendar for rules that apply broadly: the organization’s normal week, a project-specific shift, or a planned change in working hours during one phase. A similar schedule can be saved as a new base calendar and reused as a template for other calendars.1
Give one task a special calendar
Section titled “Give one task a special calendar”A task calendar is useful when one task follows a different working pattern from the rest of the project. Microsoft’s examples include machinery that runs during otherwise nonworking time and an office move that can happen only on a weekend. Create or copy a base calendar, set its work week or exceptions, and associate it with the task. The task calendar then takes precedence over the project calendar for that task.
When a resource is assigned to that task, the resource’s own nonworking time can still affect scheduling. The task’s Scheduling ignores resource calendars setting can suppress that resource-calendar effect, but it may allow work to be assigned when the resource is unavailable. The task-calendar article explains this interaction and its tradeoff.3
Give one resource a unique schedule
Section titled “Give one resource a unique schedule”A resource calendar represents the working pattern of a particular person or piece of equipment. It can differ from the organization’s general hours through different workdays, shift hours, or nonworking days. In desktop Project, choose the resource in Change Working Time, select its base calendar, and edit work-week details as needed.
Vacation and other absences can be entered as nonworking exceptions on the resource calendar. When an absence overlaps the resource’s scheduled work and no other available working time applies, Project can move the assigned work or extend its scheduled duration. One-time and recurring exceptions are supported.4
If you need to inspect each resource’s schedule on a calendar rather than only in the scheduling tables, Project Plan 365 provides a Calendar View for reviewing resource schedules. It is a practical companion when you want to see who is working, unavailable, or scheduled on particular dates.
Add holidays and other exceptions
Section titled “Add holidays and other exceptions”Project does not include preset holidays in a calendar. Add a holiday to the relevant calendar as a nonworking exception, and make it recurring when it repeats across the project. Work assigned to resources is then scheduled around the unavailable day, which can lengthen task duration when no other working time is available.