Using Multiple Calendars in MS Project: Complete Guide and Exercises

Master MS Project calendar management: base calendars, resource calendars, task calendars, and scheduling optimization through these 3 detailed exercises.

Solution: Exercises 1 to 3
1 Base Calendar Creation
Exercise 1
Create a custom base calendar for a project team that works Monday to Thursday, 8 AM to 6 PM, with a 1-hour lunch break from 12 PM to 1 PM. Define the working and non-working days.
Definition:

Base Calendar: Defines the standard working and non-working times for a project. It serves as the foundation for all other calendars in the project.

Calendar creation method:
  1. Open MS Project and navigate to Project > Change Working Time
  2. Create new base calendar with specific working hours
  3. Define working days and non-working days
  4. Set daily working hours and breaks
  5. Save and apply the calendar
Calendar Type
Base Calendar
Working Days
Mon-Thu
Hours
8AM-6PM
Step 1: Access Calendar Settings

In MS Project, go to Project menu > Change Working Time > Create New Calendar

Step 2: Define Working Days

Select Monday through Thursday as working days. Set Friday through Sunday as non-working days.

Step 3: Set Daily Working Hours

Define working hours from 8:00 AM to 6:00 PM with a 1-hour break from 12:00 PM to 1:00 PM.

Step 4: Configure Break Times

Insert a non-working time period from 12:00 PM to 1:00 PM to represent the lunch break.

Custom base calendar created with 4 working days per week, 9 working hours per day (excluding break).
Final answer:

Base calendar successfully created with Monday-Thursday working schedule, 8AM-6PM hours with 12PM-1PM lunch break.

Applied rules:

• Base Calendar Rule: Must define all working and non-working times

• Break Rule: Non-working time periods must be explicitly set

• Standardization: Base calendar affects all tasks unless overridden

Working Day
Weekend
Non-Working
Sun
Mon
Tue
Wed
Thu
Fri
Sat
Day Working Hours Break Time Status
Monday 8:00 AM - 12:00 PM, 1:00 PM - 6:00 PM 12:00 PM - 1:00 PM Working
Tuesday 8:00 AM - 12:00 PM, 1:00 PM - 6:00 PM 12:00 PM - 1:00 PM Working
Wednesday 8:00 AM - 12:00 PM, 1:00 PM - 6:00 PM 12:00 PM - 1:00 PM Working
Thursday 8:00 AM - 12:00 PM, 1:00 PM - 6:00 PM 12:00 PM - 1:00 PM Working
Friday - - Non-Working
Saturday - - Non-Working
Sunday - - Non-Working
2 Resource Calendar Assignment
Exercise 2
Assign a part-time resource calendar to a developer who works 4 days a week (Tuesday to Friday) with different hours: 10 AM to 6 PM, with a 30-minute break from 1:00 PM to 1:30 PM. Show how this affects task scheduling.
Definition:

Resource Calendar: Overrides the base calendar for specific resources. It defines when individual resources are available to work on tasks.

Calendar Type
Resource Calendar
Working Days
Tue-Fri
Hours
10AM-6PM
Step 1: Create Resource Calendar

Go to Resource Sheet > Right-click on resource > Information > Calendar tab > Create New Calendar

Step 2: Define Working Schedule

Set Tuesday through Friday as working days, with working hours from 10:00 AM to 6:00 PM.

Step 3: Insert Break Time

Add a 30-minute non-working period from 1:00 PM to 1:30 PM for the lunch break.

Step 4: Apply to Resource

Assign the custom calendar to the specific resource in the Resource Information dialog.

Step 5: Observe Task Impact

Tasks assigned to this resource will now schedule according to the resource's availability.

Resource calendar created with Tuesday-Friday schedule, 8 working hours per day with 30-minute break.
Final answer:

Resource calendar successfully assigned to developer with Tuesday-Friday schedule, 10AM-6PM hours with 1:00-1:30 PM break.

Applied rules:

• Override Rule: Resource calendar takes precedence over base calendar

• Availability Rule: Tasks can only be scheduled when resources are available

• Impact Rule: Resource calendar changes affect all tasks assigned to that resource

Working Day
Weekend
Non-Working
Sun
Mon
Tue
Wed
Thu
Fri
Sat
Day Working Hours Break Time Status
Monday - - Non-Working
Tuesday 10:00 AM - 1:00 PM, 1:30 PM - 6:00 PM 1:00 PM - 1:30 PM Working
Wednesday 10:00 AM - 1:00 PM, 1:30 PM - 6:00 PM 1:00 PM - 1:30 PM Working
Thursday 10:00 AM - 1:00 PM, 1:30 PM - 6:00 PM 1:00 PM - 1:30 PM Working
Friday 10:00 AM - 1:00 PM, 1:30 PM - 6:00 PM 1:00 PM - 1:30 PM Working
Saturday - - Non-Working
Sunday - - Non-Working
3 Task Calendar Application
Exercise 3
Create a task calendar for a critical milestone that must be completed during specific maintenance windows: weekends only, from 8 PM Saturday to 6 AM Sunday. Show how this affects the project timeline and resource allocation.
Definition:

Task Calendar: Applies specific working time constraints to individual tasks. It overrides both base and resource calendars for that specific task.

Calendar Type
Task Calendar
Working Period
Sat 8PM-Sun 6AM
Duration
10 Hours
Step 1: Create Task Calendar

Go to Task Information > Advanced tab > Calendar > Create New Calendar

Step 2: Define Maintenance Window

Set only Saturday evening (8:00 PM onwards) and Sunday morning (until 6:00 AM) as working time.

Step 3: Configure Non-Working Days

All other days and times are set as non-working to restrict task scheduling.

Step 4: Assign to Critical Task

Apply the custom calendar to the specific maintenance task requiring the restricted schedule.

Step 5: Analyze Schedule Impact

Observe how the project timeline adjusts to accommodate the restricted task scheduling window.

Task calendar created with specific weekend maintenance window: Saturday 8PM to Sunday 6AM.
Final answer:

Task calendar successfully created for critical milestone with Saturday 8PM to Sunday 6AM working window, affecting project timeline accordingly.

Applied rules:

• Hierarchy Rule: Task calendar has highest priority over base and resource calendars

• Constraint Rule: Task can only be scheduled within its defined working times

• Timeline Rule: Restricted scheduling may extend project duration

Working Window
Weekend
Non-Working
Sun
Mon
Tue
Wed
Thu
Fri
Sat
Day Working Hours Special Note Status
Saturday 8:00 PM - 11:59 PM Start of maintenance window Working
Sunday 12:00 AM - 6:00 AM End of maintenance window Working
All Other Days - Restricted scheduling Non-Working
Calendar Hierarchy and Rules
Task Calendar > Resource Calendar > Base Calendar
Priority Hierarchy
Base Calendar
Project Default
Standard working times for all tasks
Resource Calendar
Individual Override
Specific resource availability
Task Calendar
Task-Specific
Exclusive task scheduling
Key Definitions:

Base Calendar: Sets the standard working time for the entire project

Resource Calendar: Defines when individual resources are available

Task Calendar: Specifies when specific tasks can be worked on

Complete Methodology:
  1. Plan Calendar Structure: Determine if you need custom calendars
  2. Create Base Calendar: Set standard working times
  3. Define Resource Calendars: Account for individual schedules
  4. Apply Task Calendars: For specific scheduling requirements
  5. Monitor Impact: Review schedule changes and conflicts
Tip 1: Start with base calendar and customize only when necessary.
Tip 2: Use resource calendars for part-time workers or shift workers.
Tip 3: Task calendars are ideal for maintenance windows or restricted access tasks.
Tip 4: Always review the schedule after applying custom calendars.
Advanced Calendar Applications
Availability = Working Days × Working Hours × Efficiency
Resource Availability Formula
Calendar Inheritance
Concept:

Calendar Inheritance: Lower-priority calendars inherit settings from higher-priority calendars unless explicitly overridden.

Inheritance Rules:

• Resource calendars inherit from base calendars unless specified otherwise

• Task calendars inherit from resource calendars unless specified otherwise

• Changes to higher-level calendars cascade down to lower levels

Best Practices:

• Make base calendar changes sparingly to avoid unintended consequences

• Document all custom calendar modifications

• Test schedule changes before finalizing

Common Issues
Common Problems:

Calendar Conflicts: When multiple calendars have conflicting settings

Unrealistic Schedules: When calendars create impossible scheduling scenarios

Resource Overallocation: When calendars don't properly reflect actual availability

Resolution Strategies:

• Check calendar hierarchy for conflicts

• Verify resource availability matches calendar settings

• Adjust task durations based on realistic availability

Calendar Types and Specifications
Total Available Hours = Σ(Daily Working Hours) × Efficiency Factor
Capacity Calculation
Key definitions:

Working Time: Periods when work can be performed

Non-Working Time: Periods when work cannot be performed

Exceptions: Specific dates that override regular calendar patterns

Complete methodology:
  1. Analyze Project Requirements: Identify special scheduling needs
  2. Choose Calendar Type: Select base, resource, or task calendar
  3. Define Working Patterns: Set working days and hours
  4. Configure Exceptions: Add holidays, maintenance windows, etc.
  5. Test and Validate: Verify schedule accuracy
Tip 1: Use exceptions for one-time schedule changes rather than changing the base calendar.
Tip 2: Consider time zones when assigning calendars to distributed teams.
Tip 3: Regular calendar reviews prevent scheduling conflicts.
Tip 4: Document calendar assignments for project handover.
Best Practices: Always start with a base calendar, use resource calendars for individual schedules, and task calendars for unique requirements.
Common Errors: Forgetting to update calendars when schedules change, misaligning calendar hierarchies, not accounting for breaks.
Formulas to know by heart:

• Calendar Priority: Task > Resource > Base

• Working Hours Calculation: Sum of daily working hours

• Availability Percentage: (Available hours / Total hours) × 100

• Schedule Impact: Calendar changes affect dependent tasks

• Resource Allocation: Calendar determines when resources can work

Questions & Answers

Question: I don't understand when to use a base calendar versus a resource calendar versus a task calendar. Can you explain the differences?

Answer: Great question! The choice depends on scope and impact:

  • Base Calendar: Use for the entire project or organization. Examples: Standard work week (Mon-Fri, 9-5), 24/7 operations, seasonal work patterns.
  • Resource Calendar: Use for individual resources with unique schedules. Examples: Part-time employees, contractors with different hours, resources in different time zones.
  • Task Calendar: Use for specific tasks with unique scheduling requirements. Examples: Maintenance windows, restricted access periods, equipment availability.

Think of it as layers: Base calendar is the foundation, resource calendar modifies for specific people, and task calendar provides final control for specific activities.

Example: Your company uses Mon-Fri (base calendar), but John works part-time Tuesdays-Thursdays (resource calendar), and he's assigned to install software during the weekend maintenance window (task calendar).

Question: When I assign a resource calendar to a resource, does it affect all tasks assigned to that resource? How does this interact with task calendars?

Answer: Yes, resource calendars affect all tasks assigned to that resource, but there's a hierarchy:

  • Priority Order: Task Calendar > Resource Calendar > Base Calendar
  • When a resource calendar is applied, it overrides the base calendar for that specific resource
  • If a task also has its own calendar, that takes precedence over the resource calendar

This means the most specific calendar setting wins. For example, if a resource works Mon-Wed but a specific task must occur on Thursday, assigning a Thursday-only task calendar will allow the task to be scheduled on Thursday despite the resource's normal schedule.

Always check the schedule after applying multiple calendar levels to ensure it meets your requirements.

Question: How do I handle holidays and special events in multiple calendars? Should I put them in the base calendar or resource calendars?

Answer: Handling holidays and special events requires strategic thinking:

  • Company-wide holidays: Add to base calendar since they affect everyone
  • Department-specific closures: Add to resource calendars for those departments
  • Project-specific restrictions: Add to task calendars for affected tasks
  • Regional holidays: Add to resource calendars for resources in those regions

Use the "Exceptions" feature in calendar settings to add specific dates that override regular patterns. This is more efficient than manually adjusting every occurrence.

Pro tip: Create a master holiday calendar template that can be reused across projects, then customize as needed for specific projects or resources.