Introduction. Preoperative planning is an essential prerequisite for the success of plastic surgery. In procedures such as breast reduction, freehand drawings may be associated with a number of challenges during the determination of axes vertical and parallel to the surgical site. Furthermore, many procedures involve subjective maneuvers, such as attempts aimed at positioning both nipples on the same line and transferring nipple-areola complexes in a well-matched manner. Our newly designed instrument, that is, the goniometer (TG), aims to ensure metric measurements appropriate for the axes, and it may also be used in circumstances that require angle measurements. Moreover, it incorporates a canal system to facilitate surgical designing of the area, to which the nipple-areola complex will be transferred. Method. From April 2013 to September 2015, TG device was used in superior pedicle breast reduction operation of 96 patients and 50 of them were randomly selected for the purpose of study analyses. An additional randomly selected 50 patients, in whom surgical planning was based on conventional techniques were served as controls. At postoperative 1 year, symmetry analysis was carried out on patient photographs. Results. No partial or total necrosis occurred at the nipple-areola complex, and symmetrical volume and shape could be achieved in all cases. TG device exhibited superiority in all criteria used for postoperative symmetry analyses (P < .05). Conclusion. We believe that this device may effectively accelerate the planning process in various types of plastic and aesthetic operations and may help ensure symmetry, especially in reduction mammoplasty and mastopexy.