Background <p>Self-reported height and weight are pragmatic, lower-cost alternatives for objective measurements but are potentially less accurate. This study examines the accuracy of self-reported measurements in a population of emerging adults.</p> Methods <p>Participants were 603 emerging adult college students aged 18 to 24 who attend public Hispanic-Serving Institutions of higher education in California, USA. The population was heterogeneous by race/ethnicity, gender, socioeconomic position, and body size. Participants self-reported height and weight; height and weight were then objectively measured during an in-person visit.</p> Results <p>Relative to objective measurements, participants, on average, overreported their height by 1.53&#xa0;cm and underreported their weight by 0.77&#xa0;kg, leading to an average body mass index (BMI) underestimation of 0.73&#xa0;kg/m². The discrepancy between self-report and objective measures significantly differed by gender, race/ethnicity, and weight but not by age, sexual orientation, household poverty status, or disordered eating behaviors. Overall, 23.8% of participants with overweight or obesity would be assigned to a lower-weight BMI category based on their self-reported measurements (including 16.2% to normal weight).</p> Conclusions <p>In this sample of emerging adult college students, we found modest but statistically significant inaccuracies in self-reported height and weight that resulted in some misclassification of BMI-based weight status categories. Expressing self-reported BMI as a numerical value instead of categorically may be one approach to minimize bias. These results may inform bias-correction approaches in future emerging adult studies that lack the resources for in-person objective measures.</p>