Human: How to sync iPhone calendar to iCloud? Assistant: 
Sync iPhone Calendar to iCloud
1. Open your iPhone's Settings.
2. Scroll to the fourth group of options and select iCloud.
3. Scroll to the Calendars option.
4. Slide the Calendars switch right to the On position.
5. Exit Settings and open your iPhone's Calendar.
6. Tap Calendars at the bottom of your screen.
7. Check All iCloud if it isn't already checked.
8. Tap Done to view your iCloud Calendar.