You can sync Google Calendar with the Calendar app that comes on your iPhone or iPad.
1) Open the Settings app on your iPhone or iPad.
2) Touch Mail, Contacts, Calendars > Add account > Google.
3) Enter your name, your full Gmail or Google Apps address, and password.
4) Touch Next.
5)Emails, contacts, and calendar events will now sync directly with your Google Account on the web. To sync only your calendar, turn the other services off.
Now when you open the Calendar app on your iPhone or iPad, you'll see your Google Calendar events.
Sync specific calendarsIf you have more than one calendar set up in Google Calendar on the web, you can choose which calendars to sync:
1) Go to
www.google.com/calendar/syncselect.
2) Check the boxes for the calendars you want to sync.
3) In the bottom right corner, touch Save.