Google Sync can sync up to 25 Google Calendars with the Calendar app on your iOS device (your iPhone, iPad, or iPod touch).
To select which calendars to sync to your iOS device, follow these steps:
- Open the Chrome or Safari browser on your mobile device and go to https://m.google.com/sync/settings/.
Note: You need to have the language set to English (US) to sync multiple calendars.
- Select Sync.
- Sign in with your account and select your device from the list of devices you've set up for Google Sync.
- Select the calendars you want to sync, and tap Save.
- Bookmark this page so you can return to it easily.
For more information, see: Google's Set up Google Sync with iOS Calendar