Hobbit Day is celebrated on 22 September, the shared birthday of Bilbo and Frodo Baggins in J.R.R. Tolkien’s fiction.
Bilbo’s eleventy-first birthday is the occasion for the large party that opens The Fellowship of the Ring. Frodo, Bilbo’s heir and adopted cousin, is also said to have been born on 22 September. The date therefore connects the two hobbits at the beginning of the main narrative and helps explain why the party is such a significant event.
Hobbit Day is observed alongside Tolkien Week, a fan celebration associated with Tolkien’s work. The observance is not a national holiday created by Tolkien or an official date in the calendar of Middle-earth; it is a modern cultural tradition among readers, libraries, and fan communities.
The date is sometimes mixed up with 21 September, the publication date of The Hobbit in 1937. Those are separate facts: one belongs to the fictional calendar, and the other to publishing history.