In the Genesis flood narrative, Noah was 600 years old when the floodwaters came upon the earth.
Genesis gives Noah's age as part of its chronological framework. The flood begins in the 600th year of Noah's life, and the narrative later records dates in his 600th and 601st years. This makes Noah's age one of the clearest numerical details in the story.
The figure is not Noah's age when he first became a father. Genesis says Noah was 500 years old when he fathered Shem, Ham, and Japheth, whose births are presented together rather than with separate ages. Noah's total lifespan is later given as 950 years.
These numbers belong to the internal chronology of Genesis. They should not be treated as independently established historical dates in the modern sense, because the flood narrative is a religious text rather than a dated contemporary record.