THE SIZE OF NOAH'S ARK. Based on the Hebrew cubit of 18.5 inches [563.88 cm], it has been estimated that if that great boat--the Ark--was only one-half the size stated in Genesis 6:14-16 and omitting water creatures--it could still have held two or seven of each basic kind of animal and bird. The remainder of the boat was probably used for food storage. This estimate is based on the Hebrew cubit in the dimensions of the Ark. However, it is very likely that Moses used the cubit of his time--the Egyptian cubit--when giving the dimensions of the Ark. This would make that giant boat even larger.
According to Genesis 6:15, the Ark was 300 cubits long, 59 cubits wide, and 30 cubits high. The Babylonian cubit was 19.8 inches [603.504 cm] , the later Hebrew regular cubit was 17.5 inches [533.4 cm] , and the Egyptian cubit was 20.65 inches [629.12 cm] .
Based on the Hebrew cubit, the Hebrew cubit, the dimensions of the Ark would have been 437.5 feet [1,333 dm] long, 72.92 feet [222 dm] wide, and 43.75 feet [133 dm] high. With three decks in the Ark, it had 95,747 square feet [29,18 sq dkm] , and a total volume of 1,395,734 cubic feet  . Its cubic tonnage would be 13,960 [42,541 cu dkm] .
Based on the Egyptian cubit used in the time of Moses, the measurements of the Ark would be 516.25 feet [1,573 dm]long, Its width would be 86.04 feet [262 dn] wide, and its height would be 51.625 feet [157 dm]. On this basis--with three stories--its square footage would be 1,332,545 square feet [40,615 sq dkm] , and its volume would be 2,293,086.9 cubic feet [69,893 cu dkm] . Its cubic tonnage would be 22,930 [20,801,637 cu kg] .
The Ark was a barge, not a ship with sloping sides, so it had a larger carrying capacity. It has been reckoned that, even if measured by the smaller 18.5-inch [563.88 cm] cubit of later times, the Ark would have been so huge that 522 modern railroad box cars could have fitted inside it! One each of every species of air-breathing creatures in the works today could be comfortably carried in only 150 box cars.
For 4,000 years after the Ark was constructed, ships rarely exceeded 150 to 200 feet [457-6,096 dm] in length. It was not until 1854 that a ship was built with a longer length than the Ark: the Eturia, a Cunard liner constructed in England. It was not until after World War II that ships were built which had a larger volume and cubic tonnage--the ocean-going oil supertankers.