Set up multiple calendars on iPhone
In the Calendar app 
, you can set up multiple calendars to keep track of different kinds of events. Although you can keep track of all your events and appointments in one place, you don’t have to. Additional calendars are easy to set up, and a great way to stay organized.
See multiple calendars at once
To view multiple calendars, tap Calendars at the bottom of the screen, then do any of the following:
Select the calendars you want to view.
Tap US Holidays to include national holidays with your events.
Tap Birthdays to include birthdays from Contacts with your events.
Set a default calendar
You can set one of your calendars as the default calendar. When you add an event using Siri or other apps, it’s added to your default calendar.
Go to Settings
> Calendar > Default Calendar.Select the calendar you want to use as your default calendar.
Change a calendar’s color
Tap Calendars at the bottom of the screen.
Tap
next to the calendar, then choose a color.Tap Done.
For some calendar accounts, such as Google, the color is set by the server.
Turn on iCloud, Google, Exchange, or Yahoo calendars
Go to Settings
> Passwords & Accounts > Add Account > Other.Tap Add CalDAV Account or Add Subscribed Calendar.
Enter the server information.
Subscribe to a calendar
Go to Settings
> Passwords & Accounts > Add Account > Other.Tap Add Subscribed Calendar.
Enter the URL of the .ics file to subscribe to and any other required server information.
You can also subscribe to an iCalendar (.ics) calendar by tapping a link to the calendar.
Add a CalDAV account
Go to Settings
> Passwords & Accounts > Add Account > Other.Tap Add CalDAV account.
Enter the server information.
Move an event to another calendar
Tap the event, tap Calendar, then select a calendar to move the event to.