Using the common 18-inch cubit, Noah’s Ark would have been approximately 450 feet long.
Genesis 6:15 gives the Ark’s length as 300 cubits, its width as 50 cubits, and its height as 30 cubits. If one cubit is treated as 18 inches, the length converts to 450 feet, or about 137 meters. The text itself does not define the cubit, so the metric equivalent is approximate.
The dimensions produce a length-to-width ratio of 6:1, which is often discussed in relation to stability. The Ark is described as a huge rectangular vessel, not a conventional ship with a pointed bow. Modern replicas therefore use different materials and interpretations while preserving or adapting the biblical measurements.