Fort Knox doesn't store gold bars that small. A 1kg gold bar is about the size of a cellphone. The ones at Fort Knox are the large trade bars, which weigh about 400 ounces (or 12.4 Kg).

> Size of a standard gold bar: 7 inches x 3 and 5/8 inches x 1 and 3/4 inches.

> Weight of a standard gold bar: approximately 400 ounces or 27.5 pounds.

https://www.usmint.gov/about/tours-and-locations/fort-knox