This study aimed to develop and validate a short form of the Smartphone Addiction Inventory (SPAI) and determine the cut-off point for smartphone addiction based on a psychiatric interview. A sample of 281 Iranian under-graduate students from Mazandaran University of Medical Sciences complet-ed the 26‐item SPAI and psychologist interview. Stepwise multiple linear re-gression identified 10 items for the short-form of the SPAI, consisting of compulsive behavior (four items), functional impairment (three items), withdrawal (two items), and tolerance (one item) with an explained variance of 96%. Exploratory factor analysis revealed a two-factor structure that la-beled Compulsive behavior & Functional impairment (47.99 variance) and Withdrawal & Tolerance (11.57 variance). Confirmatory factor analysis (CFA) verified the structure by excellent goodness of fit indices (p-value=.061, x2/df =1.43, CFI=.99, GFI=.97, and RMSEA=.039). The inter-item and item-total correlations of the SPAI-SF were positively significant and confirmed the convergent validity. Internal consistency verified by Cronbach’s alpha of .875 (CI: .852-.896). The area under the curve (AUC) was .876 (95% CI=.833-.919, p<.001), indicating a good diagnostic efficien-cy. The best cut-off point to discriminate diagnostic negatives was 23, with a sensitivity of 79.19%, a specificity of 83.33%, and an accuracy of 80.43%. The results indicated acceptable reliability, validity, and AUC for the SPAI-SF for smartphone addiction screening and studies.