According to Genesis, Noah’s Ark was supposed to be 50 cubits wide.
Genesis 6:15 gives three measurements for the Ark: 300 cubits in length, 50 cubits in breadth, and 30 cubits in height. These dimensions describe the biblical vessel before the Flood and are usually discussed as a long, rectangular or box-like structure rather than as a ship designed for ordinary navigation.
The exact modern length of a cubit is uncertain because ancient cubits varied by culture and period. Common estimates place the Ark at roughly 135 to 157 metres long, depending on the cubit used. That uncertainty affects the modern conversion, but not the biblical figure of 50 cubits.
This measurement is sometimes confused with the Ark’s length or height. Genesis assigns 300 cubits to length and 30 cubits to height; 50 cubits is specifically the breadth, or width.