In J.R.R. Tolkien’s fictional calendar, Bilbo and Frodo Baggins shared a birthday on 22 September.
Bilbo was born on 22 September T.A. 2890, while Frodo was born on 22 September T.A. 2968. The date is especially memorable because Bilbo celebrated his eleventy-first birthday and Frodo’s thirty-third birthday together at the beginning of The Fellowship of the Ring.
Bilbo’s party takes place in Hobbiton, where he gives a speech, disappears using the One Ring, and leaves the Shire. Frodo inherits Bag End and the Ring, though Gandalf later discovers the object’s true identity and urges Frodo to leave.
The shared birthday is a useful detail for distinguishing Tolkien’s chronology from real-world dates. The films also emphasize the party, but Tolkien’s books provide the relevant Shire-calendar dates and ages. In hobbit culture, reaching the age of thirty-three marks coming of age, while Bilbo’s eleventy-first birthday is an unusually advanced celebration.