Aim: Perceived uncontrollable mortality risk (PUMR) refers to people's beliefs regarding their risk of death due to factors outside of their control. Previous theoretical models and empirical studies provide evidence that those with greater PUMR are less motivated to invest in preventative health behaviors, but little is known about how accurately people estimate PUMR compared to objective measures of risk exposure, an important consideration for interventions designed to address the link between PUMR and health behavior. Here, we explore how objective risk indices and personal characteristics relate to PUMR. Subject and methods: We performed a series of pre-registered analyses on a US-representative longitudinal study (N = 915), connecting these results to external data from the Global Burden of Diseases, Injuries, and Risk Factors Study. Results: We show that (Study 1) PUMR is associated with objective measures of risk exposure, and that (Study 2) perceptions of risk due to disease drive PUMR, and more educated individuals report less perceived risk. Additionally, we find that (Study 3) estimates of PUMR are relatively stable over a 4-month period (R = 0.7), indicating that behaviors influenced by PUMR are likely to persist over time. Finally, we show that (Study 4) those who believe they are at greater risk of dying due to factors outside of their control (i.e., greater PUMR) are less likely to engage in general health behaviors. Conclusion: By assessing the determinants of PUMR, we can create data-driven policy solutions that lead individuals to more accurate mortality risk assessments and improved health behavior.