Question: how do i sync my iphone calendar with google calendar both ways?
Answer: On your iPhone or iPad, open your device settings.
Scroll and tap Passwords & Accounts.
Tap Add account. ... 
Enter your email address. ... 
Enter your password. ... 
Tap Next.
Emails, contacts, and calendar events will now sync directly with your Google Account. ... 
Open the Calendar app on your iPhone to find your Google Calendar events.