Background <p>Syringe liposuction is widely used for submental contouring in office-based practice because it requires simple equipment and can be performed under local anesthesia. However, there is little quantitative guidance for setting target aspirated volume based on universally obtainable preoperative findings. This study aimed to develop and internally evaluate a regression equation to preoperatively predict aspirated volume using only outpatient-accessible measures.</p> Methods <p>In this single-center prospective observational study, we analyzed 63 consecutive patients who underwent submental liposuction with the syringe technique between January and August 2025, all operated on by a single surgeon. Preoperative variables included vertical length, transverse width, caliper-based skinfold thickness at the neck base, palpation-based subcutaneous firmness (score 1–3), and body mass index (BMI). The primary outcome was aspirated volume (mL) measured in the syringe at the end of the procedure. Pearson correlations were calculated, followed by multiple linear regression using the least squares method. For clinical practicality, skinfold thickness, vertical length, BMI, and firmness were selected as explanatory variables for the final prediction model. Model performance was summarized using MAE and RMSE, and internal validation was performed using bootstrap optimism correction.</p> Results <p>The cohort comprised 53 women (84.1%) and 10 men, with a median age of 26.0 years. Mean skinfold thickness was 12.3±3.6 mm, mean vertical length 3.7±0.6 cm, median BMI 21.4, and median aspirated volume 19.0 mL. Aspirated volume correlated positively with skinfold thickness (r=0.639), vertical length (r=0.587), and BMI (r=0.466), and negatively with firmness (r=−0.386). The multiple regression model showed good fit (R²=0.610, adjusted R²=0.569, F=14.63, p=5.80×10⁻¹⁰). The resulting equation was: aspirated volume (mL) = −7.3587 + 0.7904×skinfold thickness (mm) + 0.3084×vertical length (cm) + 0.8934×BMI − 4.3066×firmness (1–3). Overall prediction error was MAE 3.51 mL and RMSE 4.77 mL; 50/63 cases (79.37%) were within ±5 mL absolute error.</p> Conclusions <p>A practical regression equation based solely on simple outpatient measurements predicts submental liposuction volume with moderate accuracy. This model may support standardized planning of target aspirated volume and provide a quantitative basis for education and patient counseling in office-based aesthetic practice.</p> Level of Evidence IV <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>