Testing

Biological Age Test: Which Type Is Actually Worth It?

Medically reviewed by Dr. Michael Teplitsky, MD Last reviewed 2026-09-30

Epigenetic clocks, telomere tests, blood calculators, and fitness markers compared honestly — plus a free way to estimate your biological age

A biological age test tries to estimate how old your body seems, rather than how many birthdays you have had. The options range from consumer epigenetic clocks to free blood-biomarker calculators and simple fitness markers like VO2 max and grip strength. This guide compares them honestly, explains what each can and cannot tell you, and shows why the levers to improve your result are the same no matter which test you pick.

This article is for information only and is not medical advice. It does not diagnose or treat any condition. Talk to a clinician before making decisions based on any test result.

A biological age test estimates how worn your body appears instead of simply counting birthdays. The idea is straightforward: two people who are both 50 can have very different health, and a biological age result tries to capture that difference. Some tests read patterns in your DNA, some measure the tips of your chromosomes, and others use standard blood work or fitness markers you may already have.

Want your biological age actually measured?

Opt Health uses epigenetic testing to put a number on biological age, then retests to show whether the plan moved it.

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The catch is that these tests aren't all equally reliable, and none is a settled gold standard. This guide offers an honest comparison of the main types, so you can decide whether to pay for one, use a free version, or skip testing and act on the levers directly. For a broader look at the markers that drive aging, see our metabolic health hub and biomarkers overview. It's the anchor page for our longevity cluster, alongside how to live longer and longevity supplements.

Biological Age vs Chronological Age: The Difference

Chronological age is the number of years since you were born, and biological age is an estimate of how old your body works and functions. Chronological age only ever moves one way at a fixed rate. Biological age is meant to move with your habits, your health, and your luck.

The appeal is obvious. If your biological age is lower than your chronological age, the story is that your body is aging slower than the calendar. If it is higher, the story is that you may be aging faster. That framing is useful as motivation, but it hides a hard truth: measuring biological age precisely is still an open scientific problem. There is no single agreed method, and different tests can disagree with each other on the same person. Treat any single number as a rough estimate, not a verdict.

The guide to what biological age means covers how it is estimated and how far to trust the number.

What Each Biological Age Test Kit Measures and Costs

Among paid biological age test kits, DNA methylation tests that report a pace-of-aging clock such as DunedinPACE have the most published research behind them. For most people, an estimate from routine blood work plus fitness markers answers the same question without a kit fee.

In an eLife paper, Belsky and colleagues reported an intraclass correlation coefficient of 0.96 for DunedinPACE across 36 replicate blood samples. DunedinPACE was associated with morbidity, disability, and mortality. The code that computes DunedinPACE is publicly available.

In the BASE-II study of 1,083 older adults, DunedinPACE showed the strongest mortality association among 14 aging biomarkers. Hand grip strength and standing balance also predicted mortality.

Test	What it measures	Sample	Price at time of writing	Results in	Stated retest cadence
TruAge (TruDiagnostic)	DNA methylation: Biological Age Score (OMICmAge™), Pace of Aging (DunedinPACE™), and 11 Organ Systems Age Scores	Finger-prick blood	From $499.00	3 to 4 weeks after the lab receives the sample	Many customers retest every 3 to 6 months
Tally Health (TallyAge)	DNA methylation: epigenetic age via TallyAge clock (inspired by CheekAge)	Cheek swab	$249.00	6 to 8 weeks (processed in weeks 2 to 5)	Every 6 months
GlycanAge	Immunoglobulin G (IgG) glycans, the sugar structures on the IgG antibody: the ratio of pro-inflammatory to anti-inflammatory glycans	At-home finger prick	€499.00, shown beside a reduced €424.00 (euros only, with no US-dollar price shown)	3 to 4 weeks	Bi-annual (every 6 months) or annual (every 12 months)
Elysium Index	Saliva DNA methylation: biological age, cumulative rate of aging, and 9 system age scores	Saliva	$299.00 per kit	Approximately 6 weeks after receiving saliva sample	Not stated
Function Health (biological age)	Calculation derived from lab tests (formula not published on page)	Blood draw at a Quest Diagnostics location or at home with a licensed specialist	$365.00 per year membership (not sold separately)	Not stated	Tested twice a year (100+ tests initially, 60+ follow-up tests 3 to 6 months later)
NOVOS Age	DNA methylation: Biological Age, Pace of Aging (DunedinPACE), 11 organ and system ages, and Telomere Length	At-home finger-prick blood	$349.00 for one kit, or $299.00 per kit for orders of two or more	2 to 4 weeks after the lab receives the sample	Most people retest after 6 to 12 months
Free route (routine blood markers + fitness markers)	Phenotypic Age from 9 clinical chemistry blood markers (routine panel) plus functional fitness markers like VO2 max tracking, grip strength, and balance	Routine blood draw and physical tests	Cost of routine lab panel only (no kit fee)	Not applicable (no vendor)	Not applicable (no vendor)

The kits split four ways: pace-of-aging methylation clocks (TruAge, NOVOS Age), other methylation clocks (Tally Health, Elysium Index), IgG glycans (GlycanAge) and a lab-result calculation (Function Health). The TruAge review covers TruDiagnostic's tier-by-tier prices and its verdict on the test.

Tally Health's test kit page says the TallyAge clock was trained on cheek swabs from more than 8,000 adults aged 18 to 100.

GlycanAge claims "an in-day measurement precision of ±1 year" for its IgG glycan reading. Function Health's biological age page does not name the formula or list the markers behind the score.

In Nature Aging, Higgins-Chen and colleagues reported technical noise produced replicate deviations up to 9 years across six prominent epigenetic clocks. None of the kits in the table was tested in that study.

The kit prices in the table buy one test at the time of writing, and every company that states a retest cadence expects repeat tests. At each brand's stated schedule, the annual expense totals $498 for Tally Health (two kits) and $598 for NOVOS Age (two kits ordered together).

Function Health charges $365 for a first-year membership covering two biological age calculations. Elysium omits a recommended cadence, while GlycanAge lists only single-kit euro pricing on its store. NOVOS also offers FaceAge, a free tool that estimates how old a face appears from visible signs of aging in a photo, with no lab test involved.

In PLOS Medicine, Liu and colleagues calculated Phenotypic Age from chronological age and 9 routine blood markers in 11,432 adults. Phenotypic Age was associated with all-cause mortality after adjusting for chronological age and sex.

The biological age blood test guide lists the nine markers behind Phenotypic Age. The VO2 max watch guide covers how accurate wearable VO2 max scores are.

The Main Types of Biological Age Test

Biological age tests fall into four broad groups, and they differ a lot in how much evidence supports them. Here they are from most-hyped to most-practical.

Epigenetic (DNA methylation) clocks: these read chemical tags on your DNA that change with age. Research clocks such as the PhenoAge and GrimAge concepts were built to track health and mortality risk, not just birthdays. Consumer versions exist, but they are newer and less standardized than the research tools they are based on.
Telomere length tests: these measure the protective caps on the ends of your chromosomes, which tend to shorten with age. As a one-off consumer test, telomere length is a weak signal — it varies between labs and over time, and it does not predict individual health well.
Blood-biomarker calculators: these estimate biological age from standard lab values you may already have, such as markers of inflammation, metabolism, and organ function. The PhenoAge calculation, for example, was designed to run on routine blood tests. Many versions are free.
Fitness and function markers: simple measures like VO2 max, grip strength, gait speed, and how many times you can stand from a chair carry some of the strongest links to long-term health of anything on this list — and they cost nothing.

The pattern to notice: the flashiest tests are not always the most reliable, and some of the most useful markers are free.

The guide to how an epigenetic clock works explains the Horvath, PhenoAge, GrimAge and DunedinPACE clocks.

Which Biological Age Test Is Best?

No single biological age test is a proven gold standard, so the best choice depends on what you want from it. Below is an honest comparison on the axes that matter: cost, reliability, and what the result can actually tell you.

Test type	What it measures	Evidence as a consumer test	Cost
Epigenetic clock	Age-related DNA methylation patterns	Most promising in research; consumer versions can vary run-to-run	Higher (paid test)
Telomere length	Length of chromosome end-caps	Weak and noisy for individuals; not recommended as a decision tool	Moderate (paid test)
Blood-biomarker calculator	Inflammation, metabolic and organ markers from routine labs	Reasonable and transparent; built on standard blood work	Free to low (if you already have labs)
Fitness markers (VO2 max, grip, gait)	Cardiorespiratory fitness, strength, mobility	Strong links to long-term mortality risk; cheap and repeatable	Free to low

When to choose which: if you want a low-cost, honest starting point, use a free blood-biomarker calculator plus your fitness markers. If you are a data enthusiast who understands the limits, a consumer epigenetic test can add another data point — just do not treat it as precise. Telomere-only tests are the easiest to skip. Whatever you choose, retest the same way over time so the trend, not the single number, guides you.

The Honest Caveats Nobody Advertises

Consumer biological age tests come with real limits that vendors rarely put front and center. Knowing them protects your money and your peace of mind.

Run-to-run variation: consumer epigenetic tests can return different biological ages from two samples taken close together. A swing of several years does not always mean your body changed.
No agreed gold standard: different clocks were built for different goals, so they can disagree. There is no single test that experts point to as the definitive measure of biological age.
Correlation, not diagnosis: these tests estimate risk patterns across large groups. They cannot tell you what will happen to you as an individual, and they do not diagnose disease.
Actionability gap: even a validated result does not come with a personalized treatment. The advice that follows a high biological age is the same general advice for almost everyone.

This is not a reason to distrust the whole field. It is a reason to spend carefully and to weigh a single result lightly. A biological age test is best used as a nudge, not a diagnosis.

A Free Way to Estimate Your Biological Age

You can get a reasonable, low-cost read on your biological age from standard blood work plus a few fitness checks — no premium test required. This route is transparent, repeatable, and built on markers with strong ties to long-term health.

Run a standard blood panel: markers of blood sugar, inflammation, and organ function feed the free calculators that estimate biological age. Our biomarkers overview covers which to prioritize, and fasting insulin is one of the most useful early metabolic signals.
Check your cardiorespiratory fitness: VO2 max is one of the strongest single markers of long-term health. See how to read it in our VO2 max wearables guide.
Test strength and mobility: grip strength, gait speed, and a sit-to-stand test are simple proxies for how well your body is holding up. Declining strength ties directly to sarcopenia and age-related muscle loss.

The most important part comes after the number. Whether a test says your biological age is high or low, the levers to improve it are the same: don't smoke, build cardio fitness and muscle, eat well, sleep, and keep your metabolic markers in range. Our how to live longer guide ranks those levers by evidence, and the free health assessment maps where you stand today.

The guide to how to lower biological age covers which changes moved a measured biological age in trials.

The free biological age calculator turns nine routine blood results and your age into a Phenotypic Age estimate.

Frequently Asked Questions

What is a biological age test?

A biological age test estimates how old your body seems, rather than how many years you have lived. It uses markers such as DNA methylation patterns, telomere length, blood biomarkers, or fitness measures to compare you against typical values for your age. The result is an estimate of risk and aging pace, not a diagnosis, and no single method is an agreed gold standard.

Which biological age test is best?

There is no proven best test, so the smart starting point is a free blood-biomarker calculator plus fitness markers like VO2 max and grip strength, which have strong links to long-term health and cost little. Consumer epigenetic clocks are the most promising paid option but can vary between samples. Telomere-only tests are the weakest and easiest to skip.

Are consumer epigenetic age tests accurate?

Consumer epigenetic tests are promising but not precise for individuals. Two samples taken close together can return biological ages that differ by several years, and different clocks can disagree because they were built for different goals. They are best used to watch a long-term trend across repeated tests, not to trust a single result.

Can I test my biological age for free?

Yes. Free biological age calculators estimate your result from a standard blood panel, and simple fitness checks like VO2 max, grip strength, and gait speed add strong, low-cost signals. This route is transparent and repeatable, and it captures much of what a paid test aims to measure without the extra expense.

What should I do with my biological age result?

Use it as a nudge, not a diagnosis. The levers that improve biological age are the same for almost everyone: don't smoke, build cardiorespiratory fitness and muscle, eat a whole-food diet, protect sleep, and keep metabolic markers in range. Retest the same way over time and watch the trend rather than any single number.

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Medical Disclaimer: This content is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare provider before making changes to your health regimen.

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