RESUMEN
The Big Five Inventory (BFI) is an instrument designed to assess the personality of individuals aged 18 and above. The original version consists of 44 items divided into five sub-scales representing each of the five personality factors: agreeableness, neuroticism, conscientiousness, openness, and extraversion. The main purpose of this study was to assess the factorial structure of the 44-item BFI and the reliability of two shorter versions with 20 and 10 items. The study also aimed to present normative data for interpreting scores from the short and ultrashort versions of the BFI for the Brazilian population. A total of 3565 individuals with a mean age of 33.3 years (SD = 13.0) from all Brazilian states participated in the study, with 44.2% from the State of Rio Grande do Sul. Participants completed a sociodemographic questionnaire and the BFI. Confirmatory factor analysis showed poor adaptation of the original 44-item model, but the short and ultrashort versions with 20 and 10 items respectively had good adaptation indexes and reliability, with Omega coefficients above 0.70. Normative data for the shorter versions were presented using mean, standard deviation, and percentiles (lower, medium, and higher). The study concluded that the short and ultrashort versions of the BFI have good reliability and can be used in surveys requiring a brief personality assessment.