Background <p>Asian rhinoplasty frequently requires robust structural support to counteract a thick skin envelope. However, relying solely on septal cartilage often leads to graft depletion after preserving a safety L-strut. This study quantifies the volumetric sufficiency of the composite bony-cartilaginous unit to address this limitation while ensuring skull base safety.</p> Methods <p>A retrospective computed tomography analysis was performed on 116 Asian adults (60 men, 56 women). A standardized harvest template was virtually executed, assuming the preservation of a 10-mm L-strut. Total septal area, harvestable cartilage, and the composite bony-cartilaginous unit (cartilage, perpendicular plate of the ethmoid, and vomer) were quantified using defined anatomical landmarks.</p> Results <p>The harvestable septal cartilage averaged 461.5&#xa0;mm², which was significantly smaller in women than in men (<i>p</i> &lt; 0.001). Expanding the harvest to include the bony septum yielded a composite area of 992.0&#xa0;mm², representing a 2.21-fold increase in graft availability. Radiographic analysis established critical safety landmarks: the mean skull base angle was 123.6°, the distance from the anterior nasal spine to the cribriform plate was 48.9&#xa0;mm, and the distance to the anterior sphenoid wall was 54.3&#xa0;mm.</p> Conclusions <p>Septal cartilage is an inherently scarce resource in Asian rhinoplasty, particularly in females. Harvesting the septum as a bony-cartilaginous unit safely and reliably doubles the graft supply. With precise osteotomy trajectories, this composite graft eliminates the need for distant donor site morbidity, serving as an optimal local reserve.</p> Level of Evidence III <p>This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors <a href="http://www.springer.com/00266">www.springer.com/00266</a>.</p>