According to Genesis, the length of Noah’s Ark was 300 cubits.
Genesis 6:15 gives the ark’s dimensions as 300 cubits long, 50 cubits wide, and 30 cubits high. The passage presents these measurements as instructions given to Noah for constructing the vessel before the Flood.
A cubit was an ancient unit based broadly on the length of a forearm, so its exact modern equivalent is uncertain. Depending on the cubit standard used, 300 cubits is commonly estimated at roughly 135 to 157 metres, or about 443 to 515 feet.
The dimensions are often compared with large ships, but the Genesis account does not specify a modern naval design or a precise conversion. The length, width, and height ratio is approximately 6:1:0.6, giving the ark a broad, box-like form.