Add Google Calendar Subscriptions to your iPhone Calendar

Step 1: Write down or copy the URL for the Google Calendar you want to add to your iPhone.

Step 2: Tap the "Settings" icon, then scroll down and select "Mail, Contacts, Calendars."

Step 3: Tap "Add Account" and select "Other."

Step 4: Select the "Add Subscribed Calendar" option, fill in the Google Calendar URL in the Server box and click "Next." Change any settings you see fit before saving the calendar. You do not need a username or password.

Step 5: Toggle your view of the subscribed calendar by opening the Calendar app and tapping "Calendars" in the upper left corner. Tap a calendar name to either display or remove calendar events.

Subscribing to a Google calendar on Android

Subscribing to a Google calendar on Android is actually a two-step process. You must first subscribe to the calendar using the web version of Google Calendar and then add it to your Android device.

Subscribing to ical on Google Calendar web:
Step 1: go to Google Calendar on the web
Step 2: Choose "Other calendars"
Step 3: In the dropdown menu, choose "Add by URL"
Step 4: Insert the calendar's ical address, click "Add Calendar," and you should be all set.

Adding subscribed calendars to Android:
Step 1: On your Android device, you may have to clear the existing calendars and re-sync the data for a new calendar to show up.
  • Settings / Applications / Manage Applications / Calendar -> Clear Data
  • then Settings / Applications / Manage Applications / Calendar Storage -> Clear Data
Wait a few minutes and you should be able to see the new calendar. If it does the new calendar does not show up, also do the following:
  • Settings / Accounts & sync -> select your account, uncheck the "Sync Calendar" option 
  • Wait a few minutes and re-check the Sync Calendar option to see
Keep in mind that if you have 2-step verification enabled on your phone, you may have to remove the account entirely and re-add it.