Introduction: The World Health Organization-Five Well-Being Index (WHO-5) is a widely used self-report measure for evaluating mental well-being in both general and clinical populations. This study examines the psychometric properties of the WHO-5 using a large, representative sample of the adult population in Germany (N = 2,515) and presents updated population norms.

Methods: Analyses included item-level statistics such as means, standard deviations, and inter-item correlations. Construct validity was evaluated through correlations with measures of depression (PHQ-2), anxiety (GAD-2), somatic symptoms (SSS-8), and loneliness (UCLA Loneliness Scale). Internal consistency was measured using coefficient omega, while factorial validity was tested through confirmatory factor analysis based on a one-factor model. Measurement invariance was assessed across gender and age groups using multi-group confirmatory factor analyses. Population norms are reported for the total sample and various age groups.

Results: The findings confirm the strong psychometric properties of the WHO-5, including its internal consistency and construct validity. Measurement invariance results support comparability of scores across gender and age. The updated norms offer.

Discussion: These updated norms support the continued implementation of the WHO-5 as a practical tool for population-based prevention and mental health care planning.