Adding a Google account for calendar purposes on iOS 8.3
Have you tried the following on your iOS device:

Add Account &gt; Other &gt; Add CalDAV Calendar


Then enter your credentials:



Server: google.com
Username: Enter the email address of the associated Google account.
Password: Enter the password that is associated with the Google account from above.
Description: Purely for information. Enter a description of the account.


This should work when only using the Calendar on a Google Account.