Your chronological age increases automatically. Estimated biological age can move in either direction: it is calculated from how you live.

What this number means

Biological age is an estimate that expresses your lifestyle in years. Sleeping seven to nine hours, walking, exercising and keeping resting heart rate low can bring it below your chronological age. Short sleep and little movement can push it higher.

It is not a diagnosis or a prediction of how long you will live. It translates habits into a familiar unit: years.

How it is calculated

Decades of population research describe associations between habits and health risks. For example, risk increases by roughly 10% for each year of age. A habit associated with a 10% increase in risk therefore corresponds to approximately one year; a reduction moves the estimate in the other direction.

The bracelet uses eight measurements from the past six months, compares them with longevity research recommendations and converts the differences into years. The total is added to or subtracted from your chronological age.

The reference point is a set of recommendations rather than the average person. Biological age matches chronological age when those targets are met. For many people, the initial estimate is higher: it shows the target rather than rewarding an average result.

Eight measurements

Sleep

  • Sleep duration: a reference of seven to nine hours of actual sleep per night. Chronic short sleep is associated with cardiovascular and cognitive risks.
  • Sleep routine: how consistently the midpoint of your sleep occurs from day to day. A variation within 40 minutes is the reference; repeated shifts resemble ongoing mild jet lag.

Activity

  • Steps: benefits increase up to roughly 8,000–10,000 daily steps, then level off.
  • Zones 1–3: weekly minutes at a moderate heart rate, such as brisk walking or light cardio. The reference is at least 100 minutes per week.
  • Zones 4–5: minutes at a high heart rate, such as intervals or steep climbs. Even small weekly amounts are associated with lower risk.
  • Strength training: from 40 minutes to two hours per week. Muscle supports metabolism and bone health; the calculation does not add longevity benefits beyond two hours.

Fitness

  • VO₂max: cardiorespiratory fitness, estimated from resting heart rate, profile and activity. It has the largest weight in the calculation; low fitness is strongly associated with health risk.
  • Resting heart rate: nighttime heart rate. Below 60 is the reference; each additional 10 beats corresponds to roughly one year in this calculation.

Measurements overlap. Resting heart rate and VO₂max, for example, describe related aspects of fitness. We account for this rather than counting the same contribution twice.

Pace of aging

Biological age changes slowly because it reflects six months of your life. Pace of aging shows your recent direction by comparing the last 30 days with your six-month baseline.

  • 1x: the estimated pace matches the calendar;
  • below 1x: your recent habits are better than your baseline, tending to lower the estimate;
  • above 1x: the last month tends to raise it;
  • 2x or above: a red zone indicating a faster increase in the estimate.

Pace is an early signal. The age estimate may not have shifted yet, while pace shows its direction if the current pattern continues.

When it updates

Once a week, on Sundays. The number stays stable during the week because habits are assessed over weeks rather than individual days.

The first estimate requires 21 nights wearing the bracelet within a month. Calibration continues during the first weeks, so the value may be refined. If too few nights are recorded, calculation pauses and resumes when enough data is available again.

What it cannot tell you

This estimate does not capture nutrition, work stress, relationships or genetics. It does not replace a doctor or diagnose conditions. A favorable score can coexist with concerning laboratory results: it is a lifestyle estimate, not a medical examination.

Unlike chronological age, the estimate can decrease. Each metric shows how many years it adds or removes. Start with the largest positive contribution to identify a possible priority for change.

Sources

  • Translating risk into “effective age”: Spiegelhalter D., BMC Medical Informatics and Decision Making, 2016. Read
  • Daily steps and mortality, with benefits leveling off around 8,000–10,000 steps: Paluch A. et al., Lancet Public Health, 2022. Read
  • Sleep regularity and longevity: Windred D. et al., Sleep, 2024. Read
  • Chronic short sleep and mortality: Itani O. et al., Sleep Medicine, 2017. Read
  • Vigorous activity and mortality risk: Ahmadi M. et al., European Heart Journal, 2022. Read
  • Strength training and health risk, including the J-shaped association: Momma H. et al., British Journal of Sports Medicine, 2022. Read
  • Cardiorespiratory fitness and mortality: Mandsager K. et al., JAMA Network Open, 2018. Read
  • Resting heart rate and mortality: Zhang D. et al., CMAJ, 2016. Read

tri translates habits into an understandable estimate, but does not replace a doctor. If something concerns you, consult a professional. Biological age here describes lifestyle, not a diagnosis.