Purpose : This study aimed to present the average interpupillary distance (IPD) of Korean adults measured by three different methods and to evaluate the differences according to the measurement techniques. Methods : A single experienced examiner measured monocular and binocular distance IPD using three methods: a PD meter a PD ruler, and an auto-refractometer. The results were expressed as mean±standard deviation. Differences among the three instruments were analyzed using paired t-tests. Pearson’s correlation coefficients were calculated to evaluate relationships among the measurement methods. Agreement between two instruments was assessed using Bland–Altman plots with 95% limits of agreement (LoA; lower and upper LoA). Results : The mean age of the participants was 21±2.3 years; 47 (49.5%) were male and 48 (50.5%) were female. In all three measurement methods, males showed significantly greater IPD than females. The mean binocular IPD was 62.53±3.22 mm for the PD meter, 63.16±3.29 mm for the PD ruler, and 63.37±3.46 mm for the auto-refractometer. Paired t-tests revealed that the PD meter measurements were on average −0.64±2.84 mm lower than the PD ruler (p = 0.031) and −0.84±2.20 mm lower than the auto-refractometer (p<0.001). There was no significant difference between the PD ruler and auto-refractometer. The 95% LoA for binocular IPD were −6.21 to 4.93 mm (PD meter vs. PD ruler), −5.16 to 3.47 mm (PD meter vs. auto-refractometer), and −6.49 to 6.08 mm (PD ruler vs. auto-refractometer). Differences exceeding 3.5 mm were observed in 18.9% (PD meter vs. PD ruler), 14.7% (PD meter vs. auto-refractometer), and 21.1% (PD ruler vs. auto-refractometer) of participants. Conclusion : The mean differences among the three instruments were all within 1 mm, suggesting that the discrepancies were clinically insignificant. However, in 14.7∼21.1% of cases, differences greater than 3.5 mm may induce visual discomfort or symptoms when spectacles are fabricated based on such measurements.