God commanded Noah to build an ark 300 cubits long, 50 cubits wide, and 30 cubits tall (Gen. 6:15). Based on the Hebrew Short Cubit (17.5 inches), the ark would be 437 feet long, 73 feet wide, and 44 feet tall. At this size, the ark would have the volume capacity of 1, 396,000 cubic feet and could hold 522 railroad stock cars. Based on the Hebrew Long Cubit, the ark would be 510 feet long, 85 feet wide, and 51 feet tall.
The inside of the ark was to have three decks (Gen. 6:16). Above the second and third deck, a sub layer could have been added thus allowing more room for storage or other animals. Each deck consisted of several rooms (Gen. 6:14). There was a roof on the top (Gen. 6:16) where Noah and his family may have lived. This could have been a room with open windows to allow for ventilation. There was one door on the side of the ark.