According to Gunter JP, alar–columellar disproportions can be quantified by comparing the long axis of the nostril with the perpendicular alar–columellar distance. From the profile view, the nostril has a symmetric oval shape, with the long axis (anterior–posterior) dividing the nostril into cephalic and caudal halves. Thus, the normal distance between the alar rim to the long axis should be equal to the distance between the axis and the columella rim (Fig. 10.1). Ideally, AC distance (columellar show) should measure 2–4 mm. If AB (cephalic nostril half) is 2 mm or more, it indicates alar retraction, whereas if BC (caudal nostril half) is 2 mm or more, it indicates a hanging columella. Conversely, a decreased cephalic half implies a hanging ala, while a decreased caudal nostril half can be an indication of a retracted columella.