Objective: This study aimed to test the accuracy and reliability of measurements using digital models versus plaster models. Materials and Methods: Thirty patients were recruited in the study. Impressions were taken for all patients by alginate impression material and poured immediately using certain dental plaster with good dimensional accuracy and surface details reproduction. All casts were trimmed and polished for obtaining high quality study models. Bolton analysis was done by manual and digital techniques for all casts. Intra-operator reliability testing and Paired-samples t-tests was used to compare the measurements within groups. Results: There was an excellent intra-operator reliability for both techniques for manual and digital measurements of teeth width (ICC values are 0.998 and 0.987, respectively). paired-samples t-test for overall ratios by both techniques showed no significant difference (p value is 0.139). Conclusions: Measurements made from digital models are accurate and reliable as manual measurements.