Siddhartha Gautama traditionally attained enlightenment and became the Buddha at age 35.
Buddhist biographies state that Siddhartha left his sheltered household life at age 29. After years of study and severe ascetic practices, he abandoned extreme self-mortification and followed what became known as the Middle Way. He then meditated beneath the Bodhi Tree at Uruvela, near present-day Bodh Gaya.
At the age of 35, he is said to have gained awakening, understanding the nature of suffering, its causes, its cessation, and the path leading to cessation. From then onward he was called the Buddha, meaning “Awakened One.”
The figure 35 is based on traditional biographies and a conventional chronology, not a securely documented modern birth record. Age 29 is associated with his renunciation, while age 80 is traditionally given as his age at death. Keeping those milestones separate prevents one of the most common timeline errors in summaries of his life.