Metric’s biological age is a wellness estimate based on available Apple Health and Metric data. It is designed to summarize selected cardio-fitness, cardiovascular, body-composition, movement, and sleep signals. It is not a direct measurement of cellular age and should not be used as a standalone health conclusion.
How the estimate is assembled
- Most contributors use rolling data over roughly 90 days rather than one reading.
- Repeated signals such as resting heart rate, heart-rate variability, steps, activity, and sleep require multiple samples; some sparse signals can use fewer.
- Body-fat percentage is preferred for body composition, with lean mass used as a fallback when available.
- Rolling-window values outside the model’s plausible ranges do not contribute, and older or missing data lowers coverage.
- A missing contributor begins at chronological age instead of being silently reweighted across the remaining inputs.
What aging rate means in Metric
Aging rate compares the rolling biological-age estimate with chronological age. Metric begins presenting the rolling rate once at least seven generated daily series entries are available and limits the displayed ratio to 0.10×–3.00×. Missing contributors default to chronological age, so read the result together with its separate data-coverage indicator: a changing input, a device gap, or new data can move the estimate without proving that underlying aging has accelerated or slowed.
Different models are not interchangeable
Research uses several biological-age frameworks, including biomarker algorithms and epigenetic clocks. Metric’s wearable-data estimate should not be interpreted as equivalent to a laboratory epigenetic-age result.
The productive use is directional: check coverage, inspect which contributors changed, and focus on sustainable habits you would value even without the age estimate. Do not use a small short-term movement as evidence that an intervention changed lifespan.
Wellness and editorial boundary
Metric is a wellness product. Its scores, AI responses, nutrition analyses, and wearable-derived values are informational estimates, not diagnoses or medical advice. Results depend on the data available and may be incomplete or inaccurate. Review source data and speak with a qualified professional about health concerns.
- Metric Editorial TeamAuthor profile and review responsibilities
- Editorial policyHow Metric separates product education, evidence, and marketing
- Methodology and limitationsHow Metric describes calculations, coverage, and uncertainty
- Metric biological-age appFeature overview and interpretation guidance
- Metric scienceEvidence boundaries and source library
- Klemera–Doubal biological-age methodPeer-reviewed background on one biomarker-based framework; Metric uses a different implementation
- Horvath epigenetic clock paperBackground on a distinct laboratory-based age model
- Wearable-data biological-age researchResearch context; not evidence that Metric predicts an individual outcome