Facebook allows you to export the list of birthdays of your Facebook friends into your organizer. For this, your organizer must support the .ics calendar format, which is the case of Google Calendar, iCal, Mozilla Thunderbird, Outlook, etc…
To get started follow steps below
Step 1: Go to your Facebook account and login.
Step 2: Click Events in the left column.
Step 3: Click a search icon and then from drop down menu choose Birthdays. In here you can find all the birthdays of your Facebook friends
Step 4: Now to export those birthdays click a search icon again, and from drop down menu choose Export Birthdays
Step 5: Then select the link provided by Facebook without the webcal:// and copy it to the clipboard using the Ctrl + C.
Step 6: Click in the address bar of your web browser and paste the copied address with Ctrl + V. Confirm by pressing Enter. Save the file on your computer
Step 7: Now open your organizer software inside which you want to import your Facebook friends birthdays. Then choose File menu, Import and Export in Outlook for example.
Step 8: Select Import an iCalendar (.ics) and click Next.
Step 9: Select the ICS file that you previously downloaded and click Next.
Step 10: Then choose if you want to import birthdays into a new calendar or add to an existing calendar.
Step 11: The birthdays of your friends are then shown in your calendar.