Parental burnout (PB) is a chronic stress-related condition resulting from long-lasting exposure to overwhelming parenting stress. Previous studies showing the seriousness of this condition stressed the urgent need to provide researchers and practitioners with effective assessment tools. Validated PB measures are the Parental Burnout Inventory (PBI) and the Parental Burnout Assessment (PBA). The good psychometric properties of these instruments have been replicated across different samples and countries, but thresholds for identifying impairing PB levels (i.e., cutoff scores) have not yet been established. The present study aims to fill this gap by adopting a multi-informant and multimethod approach to a sample of 192 burned-out and control parents. PBI and PBA cutoffs were derived from the combination of several PB indicators, based on a preregistered analysis strategy. Results identified a score of 74.6 (95% confidence interval (CI) = [69.48-79.68]) for the PBI and 86.3 (95% CI = [79.49-93.03]) for the PBA as indicators of the most severe PB levels.