If you are looking for a way to keep track of when you send a greeting to celebrate the birthdays of friends and family, Google Calendar makes it easy. When you add a birthday to your Google contacts, the date is automatically synchronized with your Google Calendar and shows the birthday. All you have to do is enable the Birthdays calendar in Google Calendar.
It provides steps to add birthdays to Google Calendar from a desktop browser.
Open Google Calendar. If you don't see a menu on the left side of the window, click the menu in the upper left corner to access it.
If necessary, click the arrow to the left of My Calendar to expand the section.
Under My Calendar check the Birthdays box to enable it. If you do not see Birthdays, then click on Contacts.
As long as you have set up the birthday in Google Contacts, it should now be visible in Google Calendar.
A quick tip: Enabling the birthday calendar does not mean that you will receive notifications. If you want Google Calendar to send you a reminder, you must create a separate event in your personal calendar and enable notifications.