Bilbo and Frodo Baggins share a birthday on 22 September in J.R.R. Tolkien’s world.
Bilbo is born on 22 September 2890 of the Third Age, while Frodo is born on 22 September 2968. Their shared date is central to the opening of The Lord of the Rings, because Bilbo celebrates his eleventy-first birthday and Frodo his thirty-third birthday at the same party in Hobbiton.
The unusual celebration combines Bilbo’s coming of age with his decision to leave the Shire. During the party, he uses the One Ring to disappear, then leaves the ring behind for Frodo. That event sets the main quest in motion.
Tolkien’s birthday notation can confuse readers because Middle-earth uses calendars and dates that do not map perfectly onto modern years. In the Shire calendar, however, 22 September is the key date. Modern fans often mark it as Hobbit Day, alongside Tolkien Week, though those celebrations are later fan and cultural traditions rather than events described as holidays in the novels.