The cvunit function converts either a number or a point from one unit of measurement to another. See the acad.untfile (for AutoCAD) or the acadlt.unt file (for AutoCAD LT) for a list of units that you can convert. The syntax is
cvunit ( value, from_unit, to_unit )
The following example converts the value 1 from inches to centimeters:
cvunit(1,inch,cm)