Biological Age Test: What It Measures and How to Get One

I tested my biological age on three different platforms in 2025 and 2026. Function Health said I was 37.3. Hundred Health said 38.0. Superpower put me at 45.2. My calendar age at the time was 52.

Same blood, same body, three very different answers. That experience taught me more about what a biological age test actually measures (and what it does not) than any article I had read. If you are curious about testing your own biological age, this guide covers what the science says, the different ways to measure it, and what I learned from doing it myself across multiple platforms.

What Is Biological Age (and How Is It Different From Chronological Age)

Your chronological age is the number of years since you were born. It is a fixed number that tells you nothing about how well your body is actually functioning. Biological age, on the other hand, reflects how your cells, tissues, and organ systems are aging at a molecular level.

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Two people born in the same year can have dramatically different biological ages depending on genetics, lifestyle, nutrition, sleep quality, stress, environmental exposures, and exercise habits. Research from Steve Horvath and Kenneth Raj at UCLA established that DNA methylation patterns can serve as accurate biomarkers of biological aging across every tissue and throughout the entire life course. Their work gave rise to what scientists now call the epigenetic clock theory of aging.

The practical takeaway is straightforward. Your chronological age tells you how long you have been alive. Your biological age tells you how well you have been living. And unlike chronological age, biological age is something you can influence.

How Is Biological Age Calculated

There is no single agreed-upon method for calculating biological age, which is part of why different platforms give different results. The three most common approaches are epigenetic clocks, blood biomarker algorithms, and composite scoring systems.

Epigenetic Clocks (DNA Methylation)

Epigenetic clocks are the gold standard in aging research. They analyze patterns of chemical tags (methyl groups) on your DNA that change predictably as you age. The most well-known versions include the original Horvath clock, the Hannum clock, PhenoAge, and GrimAge. Morgan Levine and colleagues developed DNAm PhenoAge, which predicts all-cause mortality, cancer risk, and physical functioning more accurately than earlier clocks because it incorporates clinical health measures rather than just chronological age. GrimAge, published by Lu and Horvath in 2019, takes this further by using DNA methylation patterns to estimate plasma protein levels linked to lifespan, making it one of the strongest predictors of mortality and disease risk currently available.

Direct-to-consumer epigenetic testing is available through companies like TruDiagnostic (TruAge test) and Tally Health, typically costing $249 to $500 per test. These require a cheek swab or blood sample that is analyzed for methylation patterns at hundreds of thousands of locations on your DNA.

Blood Biomarker Algorithms

Platforms like Function Health, Hundred Health, and Superpower calculate biological age using blood biomarker panels rather than DNA methylation. They analyze markers like glucose, insulin, inflammation (hs-CRP), cholesterol ratios, liver enzymes, kidney function, and hormone levels, then run those values through proprietary algorithms to estimate how old your body appears based on metabolic function.

The advantage of this approach is that you get actionable data alongside the age estimate. If your biological age comes back higher than expected, the individual biomarker results show you exactly why, whether it is high inflammation, poor metabolic health, or nutrient deficiencies. The disadvantage is that different platforms use different algorithms, which is why my results varied by nearly eight years across three services. I break down the cost and value of this testing in my Function Health cost analysis.

Composite and Physical Assessments

Some approaches estimate biological age through physical performance tests like grip strength, balance, reaction time, flexibility, and cardiovascular fitness. Bryan Johnson's Blueprint protocol includes a free battery of these tests. While useful as a general health snapshot, these are less precise than molecular methods because they measure functional output rather than cellular aging directly.

I Tested My Biological Age on Three Different Platforms: Here Is What Happened

Because I use multiple health testing platforms as part of my ongoing health optimization routine, I had the unusual opportunity to compare biological age estimates from three different services within a few months of each other. All three use blood biomarker algorithms, not epigenetic clocks, which makes the comparison even more interesting because they are all working from similar raw data.

Here are my actual results.

Function Health (February 2026): Biological age 37.3, which is 15.5 years younger than my calendar age. This was based on my fourth round of comprehensive testing, covering 130 biomarkers across metabolic, cardiovascular, liver, kidney, hormone, nutrient, and inflammatory panels.

Hundred Health (March 2026): Biological age 38.0, which is 15.0 years younger. This was my first draw with Hundred, and it included 160+ biomarkers along with the integration of my wearable data from Oura and Whoop.

Superpower (November 2025): Biological age 45.2, which is 7.8 years younger. This was also a comprehensive blood panel, though Superpower's algorithm clearly weights the calculation differently.

Function Health and Hundred Health agreed within 0.7 years of each other. Superpower read nearly eight years older than the other two, despite using what should be comparable blood data. That 7.9-year spread from the same person is the most important thing to understand about biological age testing right now: the number you get depends heavily on which algorithm is doing the math.

What My Results Mean (and Why They Disagreed)

The discrepancy between my three results is not a flaw. It reflects a real debate in the health testing industry about what counts as a biomarker and how different markers should be weighted in an age calculation.

This is not an abstract issue. Function Health and Superpower are currently in active federal litigation (Case No. 2:26-cv-00810, Central District of California, filed January 2026) over how each company counts and describes its biomarker panels. The core question, “what qualifies as a biomarker?”, directly affects how biological age is calculated. For a detailed breakdown of how different platforms approach testing, see my InsideTracker vs Function Health comparison.

From a practical standpoint, I would not fixate on the specific number from any single test. What matters more is tracking your biological age over time on the same platform. If Function Health says you are 37.3 this year and 39.1 next year, that trend is meaningful regardless of what another platform might say. Consistency of measurement matters more than the absolute number.

That said, the fact that Function Health and Hundred Health were within a year of each other despite using different algorithms gives me more confidence in both platforms. My own metabolic markers support their estimates: my hs-CRP (inflammation) has been 0.2 mg/L across all four Function Health draws, my insulin sits at 2.7 uIU/mL, and my glucose, HbA1c, and lipid panels are all in optimal ranges. Those numbers are consistent with a body that is aging more slowly than average.

Types of Biological Age Tests Available in 2026

If you want to test your biological age, you have several options depending on your budget and what kind of data you want.

Blood biomarker platforms are the most practical choice for most people because they give you biological age plus a full health panel you can act on. Function Health ($365/year, two draws, 100+ biomarkers, clinician-reviewed notes) is where I would start if you want one platform. You can read my complete Function Health review for a full walkthrough, or see how it compares to Superpower. For a detailed look at whether the investment pays off, I wrote a cost breakdown of Function Health based on my four rounds of real data. Hundred Health ($499/year or $449 with my link) is newer but integrates wearable data from Oura and Whoop, which is a meaningful differentiator. Superpower ($199/year for baseline) is the most affordable entry point. I also put together an InsideTracker vs Function Health comparison for anyone deciding between those two.

Epigenetic testing through TruDiagnostic (TruAge, around $300 to $500) or Tally Health gives you a DNA methylation-based age estimate that is more scientifically validated for predicting mortality and disease risk, but it does not include the actionable blood panel data that comes with the platforms above.

Free physical assessments using grip strength, balance, and reaction time tests provide a rough estimate and are useful as a starting point, but they cannot measure what is happening at the cellular level.

Where to Get a Biological Age Test

For blood biomarker testing, Function Health, Hundred Health, and Superpower all use Quest Diagnostics for blood draws, which means you can walk into any Quest location near you. I do all of my draws at a Quest in the Cincinnati area and have never had trouble getting an appointment within a week.

For epigenetic testing, TruDiagnostic ships a kit directly to your home. You provide a sample (typically saliva or a finger prick) and mail it back. Results come in a few weeks.

If you want to start with the platform I have the most personal data with, you can skip the waitlist for Function Health here. Although Hundred Health is definitely worth a look! As of March 2026, I am still waiting on some results and the 100 day protocol, but so far I am very impressed with their platform. I will be updating my Hundred Health Review after I receive the full results and protocol.

Can You Actually Lower Your Biological Age?

Yes. And the research on this is getting stronger every year.

A landmark 2021 randomized clinical trial led by Kara Fitzgerald found that an 8-week program of diet, sleep, exercise, and relaxation guidance resulted in a 3.23-year decrease in epigenetic age compared to controls. The diet emphasized foods that support healthy DNA methylation, including dark leafy greens, cruciferous vegetables, beets, and berries. Participants also took probiotics and phytonutrient supplements.

My own results are consistent with what the research predicts. I have been following a low carb/keto diet since 2017, strength training consistently (I competed in NPC bodybuilding), tracking my sleep with Oura and Whoop, managing stress, and supplementing strategically. My inflammation marker (hs-CRP) has held at 0.2 across four rounds of testing, my insulin is 2.7, and my biological age reads 15 years younger on two independent platforms. I am not claiming my lifestyle is the only reason, but the data aligns with the published research on what slows biological aging.

The most well-supported interventions for lowering biological age based on current research include regular exercise (both resistance training and cardiovascular), a nutrient-dense diet rich in polyphenols and methylation-supporting nutrients, quality sleep (over 7 hours consistently), stress management, maintaining a healthy body composition, and avoiding smoking and excessive alcohol.

Pro Tips for Getting the Most Accurate Results

After four rounds of Function Health testing and additional draws with Hundred Health and Superpower, I have learned a few things the hard way.

Schedule your blood draw 48 to 72 hours after your last intense workout. I learned this when my ALT (a liver enzyme) spiked above range after a hard leg day. Intense resistance training, especially eccentric movements like heavy squats and lunges, causes temporary muscle cell damage that releases enzymes into the bloodstream. On paper, it looks like liver stress. In reality, it was just a timing issue, and my next draw showed ALT back at 18 U/L. I go into more detail about this in my Function Health cost analysis.

Fast for at least 8 hours before your draw. Most biomarker panels require fasting for accurate glucose, insulin, and lipid readings. I schedule early morning appointments and drink plenty of water the night before and morning of.

Stop supplements 72 hours before your draw and avoid seafood for 48 hours. Supplements can artificially inflate certain nutrient markers, and recent seafood consumption affects mercury testing.

Test on the same platform over time. Comparing your Function Health result to your Superpower result is less useful than comparing your Function Health result from February to your Function Health result from August. The trend on a single platform is where the real insight lives.

Do not panic about one out-of-range marker. Longitudinal testing teaches you the difference between a real issue and a temporary fluctuation. My hemoglobin was 8.6 g/dL after my NPC competition prep (well below the 11.7 minimum), and it fully recovered to 14.3 g/dL within a year. That recovery arc is the value of testing repeatedly.

Get the Free Blood Test Biomarker Cheat Sheet

I created a downloadable cheat sheet that breaks down the most important biomarkers to track for longevity, what optimal ranges look like, and which markers most doctors skip. Just click the button at the bottom of the email to download your copy.

Frequently Asked Questions

Biological age testing is still a developing field, and no single test gives you the complete picture. But after testing on three platforms, tracking my results over four rounds of bloodwork, and watching my biomarkers move in real time, I can say this: the value is not in the number itself. The value is in what the testing teaches you about your body and whether the changes you are making are actually working. For me, the data has been worth every dollar.

If you are ready to test your own biological age, you can skip the waitlist for Function Health here. For a deeper look at how all the major blood testing platforms compare, read my Function Health review, InsideTracker vs Function Health comparison, Is Function Health Worth It cost breakdown, Function Health vs Superpower comparison, and Hundred Health review.