Calendars are used in Project Plan 365 to schedule your project and to identify working times to determine when resources in your organization are available to work on tasks in your project.

Typically, calendars are assigned to resources so that the application can track when resources are available to work on tasks to which they are assigned. Take into account that you need to set up calendars for your project before you can assign them to resources.

To define unique or specific exceptions for working time and non-working time, you can create a task calendar.

To change the working times in your calendar, please go to the menu Project menu - Change Working Time. In the Work Weeks tab, click on the Details button and for each working day, set the working hours. For the specific working times to be applied to your project, don’t forget to go to menu File – Options – Schedule tab and change the “Default start time” and “Default end time” values, as well as “Hours per day” and “Hours per week” values to match the set working times. 

To see the calendar for a specific resource, go to the Change Working Time tab in the Project menu. Select from For calendar list any individual resource calendar.Another option is to open the Resource Information dialog for a specific resource and click the Change Working Time button. The resource’s calendar will be automatically selected in For calendar list.

To edit Resources calendar, go to the Change Working Time tab in the Project menu. Select from For calendar list any individual resource calendar and start editing.Another option is to open the Resource Information dialog for a specific resource and click the Change Working Time button. The resource’s calendar will be automatically selected in For calendar list.

To change the working time of a resource, you need to look in the resource calendar. To do this, go to the Project menu, click the Change Working Time  button and then select from For calendar list any individual resource. Or you could open Resource Information for the resource and click Change Working Time button. For the desired resource, change the working time from Work Weeks tab – Details.

You can delete a calendar from your organization projects by going to the File menu – Account Organization Information and clicking Global Settings option. A dialog will appear in which you have to click on the Organizer tab and then on the Calendars tab. After that, choose the calendar you want to delete from Global and click the Delete button.

This will affect the entire project. You can also set only just for some tasks another calendar by going to Task information dialog and in Advanced tab set the desired Calendar. By default, the Calendar is set to None so the task start and finish dates are calculated using the Project Calendar.

Note that these changes will not affect the completed tasks (100% complete) from your project.

Project calendars reflect the unique working days and hours for individual projects.