Abstract Background Fatigue is a non-specific symptom complex associated with exhaustion, lack of motivation and concentration. It has high public health relevance due to impairments in quality of life and work ability and increased risk of accidents. Fatigue has increasingly gained attention as one of the most common post-acute consequences of SARS-CoV-2 infection. Fatigue is also common among non-infected people and there is a lack of population-based background data. Therefore, we investigated the prevalence and factors associated with fatigue in a population-based epidemiological study in Germany. Methods The analyses are part of the national population-based cross-sectional telephone survey ‘German Health Update’ (GEDA 2023) in adults (3/2023-2/2024). Fatigue was surveyed using the Fatigue Assessment Scale (FAS) and dichotomized into yes (at least mild/moderate) versus no fatigue. The FAS is an instrument for mild-to-moderate fatigue, which must be distinguished from chronic fatigue syndrome (CFS). Weighted analyses of the data from 9,766 adults were carried out descriptively and in multivariable Poisson models, considering sociodemographic and health-related determinants. Results The prevalence of fatigue in Germany was estimated to be 29.7% (95% CI 28.1-31.2) and was highest in 18- to 29-year-olds at 39.6% (35.0-44.4). The prevalence decreased up to 65- to 79- year-olds (20.6% (18.2-23.3)) and was again higher in people aged 80 and over (33.2% (28.9-37.7)). Women had a higher risk of fatigue than men (aRR 1.19 (1.08-1.32)). Lower education (aRR 1.29 (1.13-1.49)) and medium education (aRR 1.13 (1.01-1.27)) were associated with increased risk of fatigue. There were significant associations between fatigue and chronic illness, depressive symptoms and long COVID. Conclusions Fatigue is a common symptom among adults in Germany. Female gender, young and very old adulthood as well as lower education are associated with higher risk of fatigue. Key messages • The correlations between fatigue and socio-demographic variables as well as parameters of physical and mental health provide important indications of groups particularly affected by fatigue. • The fatigue survey in GEDA 2023 is one of the few current European studies that describe the frequency of fatigue in the general population and analyzes health and sociodemographic determinants.