What was the length of Noah's Ark in the Genesis building instructions?

The Genesis building instructions give Noah’s Ark a length of 300 cubits. Genesis 6:15 also specifies a width of 50 cubits and a height of 30 cubits.

A cubit was an ancient unit based broadly on the length of a forearm, so its exact modern equivalent varied. Using common estimates of roughly 45 centimeters, 300 cubits would be about 135 meters, or 450 feet, but the conversion is approximate. The biblical text is certain about the cubit measurement, not a single modern metric figure.

The proportions create a long, boxlike vessel rather than a ship designed for navigation. Genesis focuses on survival, storage, and containment during the Flood; it does not describe a keel, steering system, sails, or a rudder. Modern replicas therefore differ in their conversion and engineering choices.