Bilbo Baggins is 50 years old at the start of The Hobbit. Tolkien introduces him as a respectable hobbit living comfortably at Bag End before Gandalf and the dwarves disrupt his quiet routine.
Bilbo’s age matters because hobbits traditionally value domestic comfort, regular meals, and predictable habits. At 50, he is considered an adult with an established life, but he is still young enough to undertake the journey to the Lonely Mountain. The adventure changes his reputation and his understanding of the wider world.
Bilbo later celebrates his 111th birthday in The Fellowship of the Ring, during the famous party at Hobbiton. This is a common source of mix-ups: 111 is Bilbo’s age at his birthday party, while 50 is his age when the events of The Hobbit begin.