This app was mentioned in 9 comments, with an average of 1.56 upvotes
I used this. Pretty straightforward.
https://play.google.com/store/apps/details?id=com.shadowfury.facebookcalendarsync
I've used Calendar Sync for Facebook. Kind of a weird set up process but once you get it done, it works.
I find that this works perfectly for me to sync my gmail calendar with facebook events/birthdays https://play.google.com/store/apps/details?id=com.shadowfury.facebookcalendarsync&hl=en
This will not work, because it only syncs with my phone, not with Google Calendar.
I'm using this and it works: https://play.google.com/store/apps/details?id=com.shadowfury.facebookcalendarsync