Convert from femtometer to U

Unit Definition (femtometer)
a metric unit of length equal to one quadrillionth of a meter.

Unit Definition (U)
The U is a unit of distance used to measure the height of the standard racks in which audio, video, or computer components are mounted. 1U is equal to 1.75 inches (44.45 millimeters), so that, for example, a 2U component is 3.5 inches high, and a 22U rack houses a stack of components 38.5 inches high.