According to Genesis 6:15, how long was Noah's Ark?

According to Genesis 6:15, Noah’s Ark was 300 cubits long.

The same verse gives the ark’s other principal dimensions as 50 cubits wide and 30 cubits high. A cubit was an ancient unit commonly related to the length of a forearm, but its exact standard varied by culture and period. Converting the biblical measurement into modern units therefore produces an estimate rather than one universally certain figure.

Using a common cubit of about 45 centimeters, the ark would be roughly 135 meters long, 22.5 meters wide, and 13.5 meters high. Other cubit estimates change those modern equivalents while leaving the biblical numbers unchanged.

Genesis also describes three decks, compartments, a window or opening, and a door. These specifications have inspired models and comparisons with large boats, but they do not provide enough information to reconstruct every structural detail with engineering certainty. The 300-cubit length is the canonical answer because it is the explicit measurement in the text.