According to Genesis, how long was Noah’s Ark described as being?

According to Genesis, Noah’s Ark was described as being 300 cubits long. Genesis 6:15 gives the ark’s measurements 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, so its exact modern equivalent is uncertain. Using common estimates, 300 cubits is often calculated as roughly 135 metres, although proposed values vary.

The ark’s proportions are approximately 6:1 in length to width. Modern ship designers note that this ratio would produce a broad, stable rectangular vessel, though the biblical account presents the ark as a survival vessel rather than a conventional sailing ship.

The dimensions belong specifically to the Genesis narrative. Later Jewish, Christian, and Islamic traditions add details, but those traditions do not all preserve identical descriptions of the vessel.