Biological Age Calculator

How this biological age calculator works

Your biological age is your real age, adjusted for how your body is doing. This calculator compares each number you enter with what's typical for someone your age and sex, then turns the difference into years.

The conversion comes from large studies that followed people for years and recorded who died from any cause. They show how much risk rises or falls with each measure. Risk of death also climbs with age at a steady rate: after about 30, it roughly doubles every 8 years. That pattern is called the Gompertz law. It lets the calculator say, for example, that a low step count carries the same extra risk as being two years older.

Three guardrails keep the result sensible:

• Each number is weighted down. The measures overlap (fit people tend to have a lower resting heart rate too), and wearable readings are noisy, so no factor counts at full strength.
• Each number has a cap. VO2 max can move the result by up to 6 years. Bedtime consistency can move it by up to 2.
• The total is capped at 12 years either way.

Your biological age is your real age plus the years from each number. The calculator needs at least 3 of the 7 numbers, so one odd reading can't decide the answer.

What each number is worth

VO2 max carries the most weight because cardio fitness is one of the strongest predictors of how long people live. In a meta-analysis of 33 studies, each extra 3.5 ml/kg/min of VO2 max came with 13% lower risk of death from any cause. To see where yours ranks for your age and sex, use the VO2 max calculator.

How much each change is worth

These figures hold for men and women at any age up to 60. After 60, the typical step count used for comparison eases off, so steps count for a little more.

Where to find your numbers in Apple Health

Open the Health app on your iPhone and search for each name below. Tap M at the top of a chart to see the past month, then use the average shown above the chart.

• VO2 max: search for Cardio Fitness. Apple Watch estimates it during outdoor walks, runs, and hikes, so it appears after a few of those.
• Resting heart rate: search for Resting Heart Rate.
• Heart rate variability: search for Heart Rate Variability. Apple Watch reports it in milliseconds.
• Daily steps: search for Steps.
• Exercise: add up a normal week of workouts. The Fitness app lists every one with its length.
• Sleep: search for Sleep and use the average time asleep, not time in bed.
• Bedtime consistency: think about when you fell asleep over the last two weeks, weekends included. If most nights land within half an hour of your usual time, pick ±30 minutes.

How accurate is it?

It's an estimate, not a medical test. Keep these limits in mind:

• It compares you with averages. The studies behind it describe large groups. They show that people with a higher VO2 max live longer on average, not that raising yours by 3.5 points buys exactly 1.3 years.
• Wearable numbers are estimates too. Apple Watch VO2 max, HRV, and sleep can differ from lab measurements. Use monthly averages, not a single day.
• It leaves a lot out. There are no blood tests, blood pressure, body weight, smoking, or family history here. Blood-based and DNA tests (epigenetic clocks) measure different things and won't give the same number.
• The trend matters more than the number. Check again in a month. If it moves, something real has changed.

Biological age vs Apple Health Age

Apple's redesigned Health app adds Health Age, in a new Longevity tab. It's being tested in the iOS 27.2 beta and arrives later this year, in US English first. It needs an Apple Watch and an iPhone that supports Apple Intelligence. Apple says it draws on measures like VO2 max, resting heart rate, HRV, sleep, and lab results, but it hasn't published the formula. Our Apple Health Age explainer covers what's known.

Track your biological age every day with Ness

Typing in averages gives you a snapshot. Ness works it out for you every day from Apple Health, using the same model as this calculator. It adds:

• Pace of aging: whether you're aging faster or slower than normal, once you have 8 weeks of data.
• 30-day change: whether you're trending younger or older.
• Contributing factors: the years each measure adds or takes off, next to what's typical for you.
• Apple Watch: a Biological Age card on your wrist.

Ness is an AI health coach for iPhone and Apple Watch. It also scores your sleep, recovery, strain, and stress every day, logs meals from a photo, and answers questions about your own data.

FAQ

What is a good biological age? Any biological age below your real age is good. It means your numbers beat what's typical for your age and sex. The bigger the gap, the lower your risk on average. This calculator caps the gap at 12 years either way.

Can Apple Watch calculate your biological age? Apple Watch measures every input this calculator uses: VO2 max, resting heart rate, HRV, steps, workouts, and sleep. Apple's own Health Age is being tested in the iOS 27.2 beta and arrives later this year, in US English first. Ness shows a daily biological age from the same data on iPhone and Apple Watch.

How can I lower my biological age? Raising your VO2 max helps most. Each 3.5-point gain takes off about 1.3 years, and VO2 max can move the total by up to 6 years. After that, walk more (the benefit flattens above about 12,000 steps), keep a steady bedtime, sleep 7 to 8 hours, and work out 150 to 300 minutes a week. The calculator shows your three biggest levers.

Which number affects biological age the most? VO2 max. It can add or take off up to 6 years, more than any other measure, because cardio fitness is one of the strongest predictors of how long people live. Resting heart rate is next, at up to 4 years.

Is biological age the same as Health Age or fitness age? They're related, but not the same. Each estimates how old your body acts, from different inputs. Apple's Health Age uses Apple Health data and lab results. Fitness age focuses on cardio fitness. Blood and DNA tests measure aging in your cells. Expect a different number from each, and track one over time.

How accurate is a biological age calculator? It's only as good as its inputs and its method. This one uses published studies and shows every step, but it compares you with population averages, and Apple Watch readings are estimates. Treat the result as a direction, not a diagnosis.

Why does it need at least 3 numbers? One reading can be off, and one measure says little about your overall health. With three or more, a single noisy number can't decide the answer. The Ness app uses the same rule.

Does this calculator save my data? It runs in your browser and sends nothing anywhere. It remembers your entries on this device so you can update them next time. Tap Clear to remove them.

Related reading

• VO2 Max Calculator
• HRV by Age Calculator
• Apple Health Age: What It Is and How It Compares to Biological Age Apps
• Apple Watch HRV
• Heart Rate vs Resting Heart Rate
• Sleep Debt

Sources

1. Kodama S, et al. Cardiorespiratory Fitness as a Quantitative Predictor of All-Cause Mortality and Cardiovascular Events in Healthy Men and Women. JAMA, 2009.
2. Kaminsky LA, et al. Reference Standards for Cardiorespiratory Fitness Measured With Cardiopulmonary Exercise Testing. Mayo Clinic Proceedings, 2015.
3. Zhang D, et al. Resting heart rate and all-cause and cardiovascular mortality in the general population: a meta-analysis. CMAJ, 2016.
4. Aune D, et al. Resting heart rate and the risk of cardiovascular disease, total cancer, and all-cause mortality. Nutrition, Metabolism and Cardiovascular Diseases, 2017.
5. Quer G, et al. Inter- and intraindividual variability in daily resting heart rate and its associations with age, sex, sleep, BMI, and time of year. PLOS ONE, 2020.
6. Tsuji H, et al. Reduced heart rate variability and mortality risk in an elderly cohort: the Framingham Heart Study. Circulation, 1994.
7. Dekker JM, et al. Low heart rate variability in a 2-minute rhythm strip predicts risk of coronary heart disease and mortality from several causes. Circulation, 2000.
8. Paluch AE, et al. Daily steps and all-cause mortality: a meta-analysis of 15 international cohorts00302-9). The Lancet Public Health, 2022.
9. Stens NA, et al. Relationship of daily step counts to all-cause mortality and cardiovascular events. Journal of the American College of Cardiology, 2023.
10. Lee DH, et al. Long-term leisure-time physical activity intensity and all-cause and cause-specific mortality. Circulation, 2022.
11. Cappuccio FP, et al. Sleep duration and all-cause mortality: a systematic review and meta-analysis of prospective studies. Sleep, 2010.
12. Windred DP, et al. Sleep regularity is a stronger predictor of mortality risk than sleep duration. Sleep, 2024.

This calculator is for general wellness and education. It isn't medical advice and doesn't diagnose any condition.