The Ductulator is an accurate, easy-to-use, portable calculating device that aids in the layout of air-handling systems, for sizing of ducts, and for checking existing duct systems. With simple settings, the answers to many duct sizing problems may be read directly from the face of the Ductulator. Conversion of units, Inch-Pound (I-P) to International System (SI), or vice versa, is accomplished by using the scales on one side, then reading the converted values from the scales on the other side.