Abstract: An apparatus for laying out positions for the attachment of studs having a desired center to center spacing therebetween on a base plate includes a flat layout square which is precisely dimensioned for easily marking stud positions with a marker on the base plate. The layout square includes a short arm and a long arm extending perpendicularly from the short arm. In one embodiment, the short arm has a width which is equal to the actual thickness of the stud, and the long arm has a length from the intersection of the long arm which is equal to the stud spacing. This layout square also includes a dominant indicator adjacent a free end of the long arm which is spaced from the free end by an offset distance equal to one half of the width of the short arm. In one configuration, the indicator is an outside notch in the long arm and may also further include an inside notch in the long arm.