Genesis gives Noah’s ark a length of 300 cubits.
Genesis 6:15 lists the vessel’s dimensions as 300 cubits long, 50 cubits wide, and 30 cubits high. The text also describes three decks, a door in the side, and an opening or window near the top. These details make the ark’s form more specific than a simple boat, although the narrative does not provide a complete shipbuilding plan.
A cubit was an ancient unit based approximately on the length of a forearm. Its exact value varied by culture and period, so converting the ark’s dimensions into modern metres or feet is uncertain. Using common estimates, the length is often calculated at roughly 135 to 150 metres.
The stated proportions produce a long, box-like vessel. Modern replicas, including the Ark Encounter project in Kentucky, use the biblical dimensions, but such reconstructions are interpretations rather than archaeological evidence for the original story.