BackgroundThis study aimed to translate into the Irrational Food Belief Scale proposed by Osberg into the Persian language and determine the psychometric properties of in Iranian culture.MethodsOsberg’s 57-item scale was translated into Persian by using the forward-backward method. The scale’s validity was examined using face validity, content validity, and construct validity (exploratory and confirmatory factor analysis). Its reliability was assessed with Cronbach’s alpha and McDonald’s Omega coefficient. Exploratory factor analysis and confirmatory factor analysis was performed by SPSS 28 (500 subjects) and also by AMOS 26 (500 subjects). The participants completed the demographic questionnaire and the Irrational Food Belief Scale (IFBS) over the Internet.ResultsAfter translation into Persian, the validity of the scale was determined by impact score, quantitative and qualitative face validity (modification of 10 items) and qualitative content validity (modification of 8 items), and quantitative content validity (CVR, CVI and Kappa coefficient), which were greater than 0.46, 0.86, and 0.85, respectively. In exploratory factor analysis, 30 items were removed and the remaining 27 items were loaded on five factors, including behavioral and psychological aspects, nutritional attitudes, healthy eating, controlled eating, and diet, which described 30.95% of the total variance. Confirmatory factor analysis showed that the 5-factor model was the best fitting model to explain the data.ConclusionConsidering the need for a tool about in irrational food beliefs, this tool was unable to explain all these dimensions well. It is recommended to create a new questionnaire for the Iranian culture.Supplementary InformationThe online version contains supplementary material available at 10.1186/s12888-023-04909-3.