Biological age tests explained
Levine, PhenoAge, GrimAge, Horvath, DunedinPACE, OMICmAge: they sound interchangeable, but they aren't. This guide covers what each one measures, why your results can disagree and which US providers use which method.
Prices and studies checked Nov 4, 2026
The short version
- "Levine" and "PhenoAge" usually mean the same thing. Morgan Levine built PhenoAge, and it comes in two versions: one from a standard blood test and one from a DNA test.
- There are three main families: blood chemistry, DNA methylation (epigenetic) and glycan tests. Telomere tests are a fourth, older approach.
- Most clocks give you an age. DunedinPACE gives you a speed.
- Different clocks often disagree. They measure different things, so that isn't a sign that a test is broken.
- Blood PhenoAge is the cheapest route. It's worked out from nine blood markers, so routine bloods can supply it if they include all nine.
The families of tests
Blood chemistry (such as Levine PhenoAge)
This uses ordinary pathology results plus your calendar age. The formula uses nine markers: albumin, creatinine, glucose, C-reactive protein (CRP), lymphocyte percentage, mean cell volume, red cell distribution width, alkaline phosphatase and white blood cell count. It was built on a large US population survey, NHANES (Levine et al., 2018).
It's cheap and uses standard labs. But some of its markers can change in the short term, and the score moves with them.
Epigenetic (DNA methylation) clocks
These read chemical tags on your DNA, from blood, saliva or a cheek swab. The tags shift in patterns as you age. Horvath, DNAm PhenoAge, GrimAge, DunedinPACE, OMICmAge and most branded "epigenetic age" tests sit here. They cost more, results often take weeks, and the score depends on the lab and the algorithm.
Glycan age
GlycanAge measures 29 sugar structures attached to IgG antibodies, and frames the result around chronic inflammation (GlycanAge). It isn't an epigenetic clock, so don't expect it to match one.
Telomere tests
Telomeres are protective caps on the ends of chromosomes that shorten as cells divide. Telomere length was one of the first biological age measures. TruAge reports it as one line among several rather than as the headline age.
The main clocks
Researchers group epigenetic clocks into generations by what they were trained to predict: calendar age, then disease and death, then change in health over time (Arpawong et al., preprint).
- 1st generationTrained to predictCalendar ageHorvath, HannumReads like an odometer
- 2nd generationTrained to predictDisease and deathPhenoAge, GrimAgeReads like an odometer
- 3rd generationTrained to captureChange in health over timeDunedinPACEReads like a speedometer
| Clock | Generation | The question it answers | You get |
|---|---|---|---|
| Horvath, Hannum | 1st | "How old do your cells look?" Horvath uses 353 DNA sites (Biogerontology, 2026) | An age in years |
| PhenoAge (Levine) | 2nd | "How old does your health look?" The DNA version uses 513 sites (Levine et al.) | An age in years |
| GrimAge | 2nd | "What's the long-term risk?" Described as consistently the strongest epigenetic predictor of mortality (preprint) | An age in years |
| DunedinPACE | 3rd | "How fast are you aging right now?" Built from 19 markers tracked at ages 26, 32, 38 and 45 (Belsky et al., 2022) | A rate (1.0 = average) |
| Brand clocks (OMICmAge, APEX) | Varies | Set by each brand | Usually an age, sometimes system or organ ages |
Odometer or speedometer
Age clocks such as Horvath, PhenoAge and GrimAge work like an odometer: they estimate how much aging has built up. DunedinPACE works like a speedometer: it estimates the pace now. A result of 1.0 means one year of biological aging per calendar year, and 1.2 means about 20% faster (Clinical Epigenetics, 2025). Its developers report high test-retest reliability (Belsky et al.), which is why it's often used for repeat testing.
Organ and system ages
Some tests split your result into separate ages for the heart, liver, kidneys and so on. TruAge reports 11, Elysium Index nine, and Superpower sells a separate Organ Age Panel. These are newer than the headline clocks and aren't a diagnosis. Questions about a score are for your doctor.
Why results disagree
- They measure different things. In one study of 86 women, PhenoAge and GrimAge results moved together moderately (r = 0.54), while DunedinPACE had little correlation with PhenoAge (0.03) or GrimAge (0.14) (Ferreri et al., 2026).
- Scores shift between tests. One research group reports that re-testing the same person can move results by 0.9 to 2.4 years (Aging Cell, 2026). In its 2022 study, technical noise made repeat runs of the same sample differ by up to 9 years on six well-known clocks. Its retrained "PC" versions agreed within 1.5 years for most repeats (Higgins-Chen et al.).
- Everyday life adds noise. Clocks are highly consistent when the same sample is run again, but much less stable across samples taken hours or days apart, around meals, stress or pollution (Aging Cell, 2026).
There's also no consensus yet on how these measures should be validated before clinical use (Moqri et al., Nature Medicine, 2024). So a one- or two-year change on a single retest may be noise. Comparing the same clock from the same provider, under similar conditions, gives a fairer trend.
Disclosure from the 2026 study of 86 women: four authors work for TruDiagnostic, which sells the TruAge test listed below. Its figures are for the age-acceleration versions of PhenoAge and GrimAge, from a side analysis in a diet study.
Disclosure from the 2022 paper: two authors built metrics licensed to Elysium Health through Yale University, Elysium provided some of the data, and one author was a paid Elysium adviser. Elysium sells the Index test listed below.
Which US providers use which method
Prices are in US dollars, from each provider's own site. Grouped by method, not ranked. Compare listings carry their own check dates on the DNA and blood test tables; everything else here was checked Nov 4, 2026.
Blood-based
| Test | Method | Sample | What you get | Price |
|---|---|---|---|---|
| Function Health | Calculated from lab results. Function's own page doesn't name the formula. A 2024 TIME article described it as based on PhenoAge. FunctionTIME | Blood draw | Biological age, tested twice a year | $365/yrmembership, includes it |
| Superpower | "A PhenoAge estimate", in Superpower's words. It doesn't publish the calculation. SuperpowerPanels | Blood draw | BioAge and a Pace of Aging score (see the note below). An Organ Age Panel is a separate $99 test. | $199/yrmembership, includes it |
| Everlywell 360 | Nine biomarkers. Everlywell doesn't name the markers or the formula. Everlywell | Lab draw | Biological age alongside a wider panel | $399/yrmembership, includes it |
| InsideTracker InnerAge | InsideTracker's own calculation. Formula not named. InsideTracker | Blood draw | Biological age from 17 biomarkers (men) or 13 (women) | $249on its InnerAge page; our compare page lists its $489 membership and blood test |
Epigenetic and glycan
| Test | Method | Sample | What you get | Price |
|---|---|---|---|---|
| TruDiagnostic TruAge | Epigenetic: OMICmAge and DunedinPACE, both named on the product page TruAgeTruAge + TruHealth | Finger-prick blood | Biological age, pace of aging, 11 organ-system ages, telomere length, immune cell, smoking and alcohol reports | $499$849 with TruHealth's blood biomarkers |
| Elysium Index | Epigenetic: Elysium's own APEX platform, developed in partnership with Morgan Levine Elysium | Saliva | Biological age, cumulative rate of aging, nine system ages | $299per kit |
| Next Health | Epigenetic age test. Clock not named. Our listing | Not stated | One part of an in-clinic program | $15,000the Executive Physical, a wider clinic program |
| GlycanAgeNot on our compare list; for context | Glycans on IgG antibodies, not an epigenetic clock GlycanAge | Finger-prick blood | An inflammation-based biological age and a specialist call | $499$849 for two. The page doesn't name the currency. |
- Superpower's Pace of Aging isn't DunedinPACE. It comes from the same blood draw, and Superpower doesn't publish how it's calculated. TruAge is the only test on this list that names DunedinPACE.
- Everlywell uses nine markers, the same number as blood PhenoAge, but doesn't say whether it uses that formula.
- Sample type. PhenoAge, GrimAge and DunedinPACE were built on blood. Elysium's saliva test uses its own platform.
- Tally Health isn't listed. Its TallyAge kit page no longer exists, and no test was among the products in its store when we checked on Nov 4, 2026, though its site still mentions TallyAge.
- In Australia? See the Australian version of this guide.
What to compare
| If you're looking for… | Method to look for | Where it's sold |
|---|---|---|
| The lowest cost | Blood PhenoAge | Your existing bloodwork, if it has all nine markers, or a blood membership that includes one |
| A measure of current pace | DunedinPACE | TruAge |
| A clock trained on mortality | GrimAge | None of the US tests here names it on its product page |
| No blood sample | Saliva or cheek swab | Elysium Index |
| An inflammation-based signal | Glycans | GlycanAge |
These match a stated fact about each test. They aren't recommendations, and whether to test at all is a question for your doctor.
FAQ
Is Levine the same as PhenoAge?
Mostly, yes. Morgan Levine led the research behind PhenoAge, so "Levine PhenoAge" and "PhenoAge" usually mean the same model. Check whether a provider means the blood version or the DNA version (DNAm PhenoAge), because they are different tests.
Which test is most accurate?
There is no single accurate biological age, because each clock answers a different question. GrimAge is described as consistently the strongest epigenetic predictor of mortality, in a preprint not yet peer reviewed. DunedinPACE was built for repeat testing, using only DNA sites with high test-retest reliability.
How often do people retest?
There is no agreed interval. Some providers build in a schedule: Function tests twice a year, and InsideTracker suggests every 3 to 6 months. Because results vary between samples, a trend across several tests says more than any single change.
Are these tests sold in Australia?
Function and Superpower list US states only. Australia has its own providers, listed on our Australian version of this guide.
Can I lower my biological age?
Studies link diet, exercise, sleep and stress to these scores. Whether a lower score means a longer or healthier life for any one person is still being studied.
My biological age jumped several years in six months. What does that mean?
We can't interpret a result for you, so that's a question for your doctor. In general, blood PhenoAge uses CRP, white cells and glucose, which can change in the short term, and the repeat-test figures above show how much scores can move between samples.
How this guide was made
Drafted with Claude. We read each study and provider page cited here on Nov 4, 2026; "not named" means we looked and the provider's page didn't say. One source, the paper on clock generations and GrimAge, is a preprint that hasn't been peer reviewed. See how we choose and the glossary.
Not medical advice. Biological age tests aren't diagnostic tools. Talk to your doctor about any result. No provider can pay to be listed or for a better position.