In the biblical Book of Genesis, how long was Noah's Ark?

In the biblical Book of Genesis, Noah's Ark was 300 cubits long. Genesis 6:15 gives the vessel's dimensions as 300 cubits in length, 50 cubits in width, and 30 cubits in height.

A cubit was an ancient unit based approximately on the length of a forearm, but its exact size varied by culture and period. Using a common estimate of about 44–52 centimeters, the ark would have been roughly 135–156 meters long.

The dimensions are part of the biblical narrative's detailed construction instructions. Genesis also describes three decks, interior compartments, and a roof or opening. The text does not provide a modern engineering plan or specify exactly which cubit standard it uses.

The ark's stated length-to-width ratio is 6:1, a proportion sometimes compared with later cargo vessels. Such comparisons do not establish that the biblical account describes a historically verified ship, but they help explain why the dimensions remain a frequent subject of discussion.