Abstract: A T-square attachment that is designed for use in conjunction with a conventional tape measure. The square is attached to the case of the tape measure in such a way that it forms a right angle with the extended tape, so as to enable a user to mark two parallel straight lines in a perpendicular direction at selected distances measured from the end of the tape. In order to complement the size of standard lumber used in construction in the United States, the ruler portion of the T-square is approximately 1 and 1/2 inches wide and about 8 inches long. These dimensions enable a user to mark both top and bottom plates with two parallel lines to delineate the exact location for the placement of each stud. A centrally located notch in the ruler is provided to line it up with the desired markings on the blade of the extended tape measure.