Convert from fist to em

Unit Definition (fist)
The fist is an informal unit of distance equal approximately to the hand (10 centimeters or 4 inches). The unit represents the width of a clenched fist.

Unit Definition (em)
The em is a printer's unit of relative distance. One em is the height of the type size (in points) being used. If 12 point type is being set, then one em is 12 points, and so on.