Contributor view
See what pulls the estimate in either direction.
Cardio, recovery, activity, sleep, blood pressure, and body-composition signals remain visible instead of disappearing behind one age.
Biological age in Metric
See how your current physiology compares with your calendar age.
Metric estimates biological age from available Apple Health signals across cardio fitness, heart recovery, blood pressure, body composition, daily activity, and sleep. The result is a directional view of which contributors are pulling the estimate younger or older—not a forecast of lifespan or a diagnosis.
- Multiple Apple Health contributors
- Stable rolling windows
- Coverage-aware estimate
The useful answer
An estimate is more useful when you can inspect the ingredients.
Metric uses VO₂ max, resting heart rate, HRV, paired blood pressure, BMI, body fat or lean-mass ratio, daily steps, activity load, sleep duration, and sleep regularity when those signals are available.
Most contributors use rolling windows and minimum sample counts so one unusual day has less influence. Missing contributors remain neutral rather than silently giving extra weight to the data that happens to be present.
Inside Metric
Designed to keep the context attached.
Every summary should lead back to the signal, date range, or source that shaped it.
Rolling signal
Follow movement, not daily noise.
Stable windows make the estimate better suited to long-term habit review than reaction to a single reading.
Coverage matters
Know when the picture is incomplete.
Metric lowers confidence when coverage is weak and keeps missing contributors neutral rather than manufacturing precision.
How it works
Three steps from data to a better question.
Connect relevant categories
Allow the cardio, activity, sleep, blood-pressure, and body-composition signals you are comfortable sharing.
Build stable history
Recent, repeated samples provide a stronger estimate than sparse or one-time readings.
Review contributors
Use the direction of change to decide which underlying trend deserves a closer look.
What to know first
Useful, with clear limits.
- Biological age is a model-based estimate and different methods use different inputs and assumptions.
- Sparse history, missing categories, a changed device, or a changed data source can move the result or lower confidence.
- The estimate does not predict an individual lifespan and is not a diagnosis or screening result.
A good fit if
- You want one directional summary across several long-term health signals.
- You are willing to look past the headline and review the contributors.
- You have recent Apple Health history across more than one category.
Probably not for you if
- You expect a laboratory, DNA-methylation, or blood-test age from wearable data alone.
- You want a precise prediction of lifespan or future disease.
- You have too little source data to form a meaningful trend.
Common questions
The short version.
How does Metric calculate biological age?
Metric combines available cardio fitness, heart recovery, blood pressure, body composition, activity, and sleep signals using stable windows and coverage checks.
What happens when a metric is missing?
A missing contributor stays neutral at chronological age instead of being redistributed into the signals that are present. Confidence is lower when coverage is weak.
Why can the estimate change?
New samples, rolling-window changes, improved coverage, and changes to a Health data source can all affect the result.
Sources and context
Read the primary material.
Official platform documentation and original research are linked for context, not used to overstate what one app view can conclude.
Aging
An epigenetic biomarker of aging for lifespan and healthspan
A primary research example of a biological-age model built from biomarkers. Metric uses a separate model based on available Apple Health signals.
Apple Developer
HealthKit framework overview
Apple explains HealthKit as a user-controlled repository for health and fitness data from iPhone, Apple Watch, apps, and compatible devices.
Apple Support
Manage Health data on iPhone, iPad, or Apple Watch
Apple’s guide to data sources, app access, source priority, manual entries, and permission controls in the Health app.
Metric for iPhone
Make your health history easier to use.
Connect only the categories you choose. Start with the dashboard, then go deeper when a trend earns your attention.
Download on theApp Store