IPad ipad iphone how to synchronize calendars with iCloud?

Use the same Apple ID, and then turn on the calendar synchronization function. Take the iPhone 7 as an example. The specific method is as follows:

First click the "Settings" icon on the mobile phone desktop, as shown in the figure.

2. Then select the "password and account number" option in the setting interface of the mobile phone, as shown in the figure.

Third, then open "iCloud" to enter, as shown in the figure.

Fourth, after entering the iCloud interface, just turn on the switch in the "Calendar" column.

5. Then drop down the page to find the "iCloud Cloud Backup" item, and click Enter.

Sixth, finally turn on the switch of "iCloud Cloud Backup".