The Saving Inventory - Revised (SI-R) is the most widely used self-report measure of hoarding symptom severity. The goal of this study is to establish a firm empirical basis for a cutoff score on the SI-R and to examine the functioning of the SI-R as a screening tool and indicator of hoarding symptom severity across the lifespan. This study used archival data from 1,116 participants diagnosed with a clinical interview in 14 studies conducted by research groups who focus on hoarding. We used receiver operating characteristic (ROC) analysis and the Youden's J statistic to determine optimal cutoff scores for classifying participants who would be likely to receive a hoarding diagnosis. Overall, the discriminant performance of the SI-R Total score and each of the three subscales was high, confirming the status of the SI-R is an excellent screening tool for differentiating hoarding from non-hoarding cases. The optimal SI-R Total cutoff score is 39, although analyses suggested that older adults require a significantly lower cutoff and adults younger than 40 years require a significantly higher cutoff score. The confidence interval around the optimal cutoff for the SI-R Total score for oldest age group was wide in comparison to those reported for the younger groups, creating more uncertainty around the optimal cutoff score for this group. This paper provides investigators and clinicians with the data necessary to select evidence-based cutoff scores on the SI-R that optimally suit their relative need for sensitivity and specificity in different age groups.