Any user with relevant permissions can create an unlimited number of calendars from scratch and also use those calendars that were shared by other users.

To create a calendar, navigate to the Calendar section and select Add calendar → Create New

3 easy steps to create a calendar

Set Start and End Date Fields. You can set different date custom fields for each calendar. Go to Calendar's Cog/Set-Up and on the main page choose Start Date Custom field and End Date Custom Field. Here only existing date or date-time custom fields can be selected from the dropdown menu.

Create a Calendar. Any user can create an unlimited number of calendars.

From the main menu JIRA you should go to the "Calendar" and on the right side click "Add Calendar" then chose the "Create New" link.

Customize a Calendar. Any user who has edit calendar permission can set up custom fields in calendar events and their legends. You can create calendars for different cases: planning specific project or a product, employee, group of employees or the special issue types (such as a vacation or a business trip, or marketing activities).

To tune in your calendar, you could go to the "Calendar" on the main tab, and on the right side click "Calendar's Cog" then choose "Set Up" link.