Biological age is a snapshot of how your body is performing compared to others your age. While your chronological age counts birthdays, your biological age looks at key biometrics to reveal whether you're trending younger, aligned with, or older than typical for your age group. It's just an estimate—but it can be a powerful way to understand how your body is doing.
We analyze five biomarkers that widely agreed upon research ties most closely to long-term health:
Resting heart rate: a marker of cardiovascular fitness
Heart rate variability: a marker of recovery and resilience
Sleep duration: how much you're actually sleeping each night
Daily activity: how much you're moving, measured in steps
BMI: based on your height and weight
Each one is compared against benchmarks for your age and sex, and together they produce your biological age score.
We designed this algorithm with research from the following studies:
López-Otín, C., et al. "Biological Versus Chronological Aging." Journal of the American College of Cardiology, 2020.
Moqri, M., et al. "New insights into methods to measure biological age: a literature review." Frontiers in Aging, 2024.
Zhang, G.Q., and Zhang, W. "Heart rate, lifespan, and mortality risk." Ageing Research Reviews 8, no. 1 (2009): 52–60.
Empana, J.P., et al. "Association between change in heart rate over years and life span in the Paris Prospective 1, the Whitehall 1, and Framingham studies." Scientific Reports, 2024.
Lehrer, P., and Eddie, D. "Heart rate variability and biological age: implications for health and gaming." Biofeedback 41, no. 1 (2013).
Castillo-Aguilar, M., et al. "Heart Rate Variability and Exceptional Longevity." Frontiers in Physiology, 2020.
Sammito, S., et al. "Heart rate variability: a multidimensional perspective from physiological marker to brain-heart axis disorders prediction." PMC, 2025.