Genesis 6:15

And thus shall you make it: The length of the ark shall be three hundred cubits, its width fifty cubits, and its height thirty cubits

Other versions

King James Version

And this is the fashion which thou shalt make it of: The length of the ark shall be three hundred cubits, the breadth of it fifty cubits, and the height of it thirty cubits.

English Standard Version

This is how you are to make it: the length of the ark 300 cubits, its breadth 50 cubits, and its height 30 cubits.

New International Version

This is how you are to build it: The ark is to be 450 feet long, 75 feet wide and 45 feet high.