Context: Body mass index percentiles are widely used to determine overweight and obesity status in children and adolescents. Their limitations in clinical settings can be addressed. Objective: Reference ranges for the tri-ponderal mass index percentiles of Korean children and adolescents are presented for a comparison of their clinical variables with those of body mass index. Design: Cross-sectional study. Setting: Korea National Health and Nutrition Examination Survey, 2007-2016. Patients: Korean children and adolescents aged 10 to 20 years. Main outcome measures: The age- and sex-specific least mean square parameters (skewness, median, and coefficient of variation) for the tri-ponderal mass index of 9749 subjects aged 10 to 20 years. Results: The factors associated with metabolic syndrome, except diastolic blood pressure, were more likely to be worse in the subjects with tri-ponderal mass index values indicative of overweight status than in those with normal tri-ponderal mass index values. Body mass index tends to underestimate obesity-related comorbidities more than tri-ponderal mass index does. Conclusion: The tri-ponderal mass index standard deviation score may be advantageous when defining overweight and obesity in children and adolescents.