Biological age is an estimate of how much age-related change your body has accumulated, expressed in years so it can be compared against the calendar. It is a model output rather than a measured quantity — which is why the provider you choose changes the number you get.
Five consumer providers dominate biological age testing, and they do not measure the same thing. Two read chemical tags on DNA, one reads sugar structures on antibodies, one runs a formula over routine blood markers, and one reports age as a by-product of a much broader wellness panel.
That is why "which one is best" has no single answer and why cross-shopping on price alone produces a purchase people regret. This page compares all five on one rubric, then maps the five real buying questions onto the test that answers each.
The Verdict
The five providers, side by side
Listed alphabetically by provider name. Prices are typical 2026 list bands and move with promotions and bundles.
| Provider | Methodology | Sample | Typical cost | What you get back | Notes |
|---|---|---|---|---|---|
| Elysium Health (Index) | DNA methylation | Saliva | $250–$500 | A biological age plus a cumulative pace measure | Saliva collection is the easiest of the group; reports fewer sub-scores than blood-based methylation panels |
| GlycanAge | IgG glycan profile | Dried blood spot | $300–$500 | An inflammation-weighted age | Tracks chronic inflammation more directly than methylation does; smallest published dataset of the four methodologies |
| Thorne (Biological Age) | Biomarker composite | Blood — check which collection type the current product uses | Check the current product page; historically the cheapest of the group | An age derived from routine markers such as HbA1c and the albumin/globulin ratio, plus the markers themselves | The most directly actionable, since you see the inputs; the number depends entirely on Thorne's chosen formula |
| TruDiagnostic (TruAge) | DNA methylation | Dried blood spot | $230–$500 | Multiple clocks including a pace-of-aging rate, plus system-level sub-scores | The most detailed output of the group; also the easiest to over-read, since it reports many numbers at once |
| Viome (Full Body Intelligence) | RNA expression composite | Blood, saliva, stool | $400–$600 | A biological age inside a much broader wellness report | Biological age is a secondary output here — the product is primarily a microbiome and gene-expression report, and it returns the widest data set of the group if you want that in the same purchase |
The column that most often decides the purchase is the fifth one. A test that returns a single number is easy to read and hard to act on. A test that returns multiple clocks plus system-level sub-scores gives you more to work with and also more opportunity to over-interpret — a sub-score moving three years between draws is well within the method's own noise, and reading it as a finding is the most common way people misuse these reports.
Match the test to the question
| What you actually want to know | What to buy | Why | Where to get it |
|---|---|---|---|
| "Am I aging faster or slower than a calendar year?" | A pace-of-aging measure such as DunedinPACE | It reports a rate, not an age, so the baseline problem that plagues single readings largely disappears | Elysium and TruDiagnostic both report a pace measure; check current clock inclusion before buying |
| "Is my inflammation load driving this?" | A glycan-based test | IgG glycan patterns respond to chronic inflammatory burden more directly than methylation | GlycanAge |
| "What should I actually change this year?" | A standard blood panel read against optimal ranges | Fasting insulin, apoB, HbA1c and hs-CRP name a specific fix; a composite age does not | Any testing platform, or your own physician |
| "Did my two-year intervention work?" | The same methylation test you baselined on, retested under matched conditions | Cross-vendor comparison is meaningless; only same-lab, same-conditions retests are interpretable | Whichever you started with |
| "I just want the number for curiosity" | The cheapest composite, or a free calculator | Curiosity does not justify $500, and a composite gives you the underlying markers too | Thorne, or a free questionnaire with expectations set accordingly |
Row three deserves emphasis because it is the row most buyers skip. A biological age score aggregates many signals into one number, and aggregation is lossy in exactly the direction that matters: it discards the part that tells you what to do. An apoB in the top quartile, a fasting insulin of 14, or an hs-CRP of 4 each name a specific problem with a specific fix. "Biological age 47" names nothing. The biomarker guides cover the panel worth running first.
What the price actually buys
The sticker price on a biological age test is misleading in the same way a gym joining fee is. A single reading tells you almost nothing on its own, because there is no personal reference point to compare it against and population percentiles are too coarse to act on. The information appears in the second reading.
That doubles the true cost. A $300 methylation test is a $600 purchase spread across a year, and a $500 one is $1,000. Set against that, a $150–$250 composite that also returns the underlying markers starts to look different — you get an aggregate number and a set of individually actionable results for less than the cost of one premium reading. That trade-off is the strongest practical argument for the cheapest methodology in the table, and it is the opposite of how the category is usually ranked.
Does a more expensive test buy more accuracy?
Not in the sense most buyers mean by it. Price in this category tracks what the laboratory work costs and how much report you get back, and neither of those is the same thing as knowing your own number more precisely.
What the extra money genuinely pays for is real enough. Methylation arrays and glycan chromatography cost more to run than a formula applied to routine blood markers, which is most of the gap between the cheap end and the expensive end of the table above. Above that, price buys report breadth, several clocks instead of one, system-level sub-scores, and sometimes an included interpretation call that a cheaper vendor sells separately.
What it does not buy is a tighter number. Within-person test-retest variation of roughly 2 to 4 years is a property of the assay and the clock, not of the sticker. Two methylation products running the same class of array carry broadly similar noise whether one charges $230 and the other $500. Paying more returns more numbers, each carrying about the same uncertainty as the single number a cheaper test returns, which is why a premium report is easier to over-read rather than easier to trust.
The two things that actually narrow what you can conclude are available across the price range: a published test-retest precision figure, and a clock reporting a pace of aging rather than an age. Both are worth paying for. Neither reliably correlates with being the most expensive option on the page.
How to vet a specific test before you buy it
The comparison above sorts the category. Five checks sit underneath it and apply to any product in this space, including ones not listed here, and all of them are things you can verify yourself in about ten minutes on a vendor's own site.
| Check | What to look for | How to verify it | What a weak answer looks like |
|---|---|---|---|
| Do the cited papers test the product, or the field? | At least one peer-reviewed paper running the vendor's own assay and clock, ideally replicated by a group with no commercial stake in it | Work down the vendor's publications page and sort each citation into one of two piles: papers that ran this product, and papers establishing that the underlying biology is real. Only the first pile says anything about the number you will be sent | A long citation list where every entry is in the second pile |
| Is the test-retest precision published? | A stated within-person variation figure, so you know how large a change has to be before it means anything | Look for a reported test-retest or technical replicate figure. If it is absent, treat the reading as having several years of noise around it | A precision claim about the laboratory assay only, which is a different and much easier question than reproducing a person's score |
| Does the claim match the training target? | A clock validated against the outcome the marketing invokes, such as mortality or disease incidence | Check which clock generation the product runs. First-generation clocks were trained to predict calendar age, so they cannot support a claim about aging faster than the calendar | Mortality language attached to a product running a clock trained on chronological age |
| What arrives at the sticker price? | A report that states which conditions and confounders move the score, so the number can be placed in context without a paid call | Open a sample report before buying. Most vendors publish one, and it shows exactly what lands in your inbox | A score and a percentile, with everything explaining them held behind a paid consultation |
| Is a matched retest priced in? | Bundle pricing, or a stated retest cost, since one reading has no reference point | Add the retest to the sticker before comparing against another provider | A single-kit price compared against a competitor's bundle |
The first row is the one that separates the category most sharply. Nearly every vendor cites peer-reviewed research, and the research is usually real. The question worth asking is narrower: does a cited paper test the assay you are buying, or does it establish that the underlying biology is sound and leave the commercial product unexamined? Both are common, and only the first supports a claim about the number you will receive. The fourth row is the one people notice after the fact, when a result arrives as a percentile with no indication of what it is sensitive to, which is the point at which a $400 test becomes a prompt to buy a consultation.
What none of these tests can tell you
None of them tells you how long you will live, and none has shown that acting on its number changes an outcome. The population-level evidence is real: second-generation methylation clocks predict mortality across large cohorts better than chronological age does. The individual-level inference is where the marketing outruns the science, because within-person test-retest noise of 2–4 years is the same size as the change a year of genuine effort produces.
It is also worth knowing what moves these numbers that has nothing to do with aging. Acute inflammation, recent illness, sleep debt, a hard training block, and vaccination within the prior two weeks all shift composite and second-generation clock outputs. A reading taken during any of those is measuring your week, not your biology. The biological age hub covers the four methodologies in depth, and how to lower biological age covers what actually moves the number over years rather than weeks.
Which test responds fastest to a lifestyle change
Response speed is a real difference between these tests, and it is the axis providers compete on hardest once you start asking about retesting. Glycan and immune-based measures are reported to shift over a few months. Most methylation clocks move far more slowly, because they integrate across years by design.
Faster is not automatically better. A measure sensitive enough to register four months of training is equally sensitive to a chest infection, an injury, or a badly slept fortnight. Speed of response and specificity to aging pull against each other, and a provider advertising the first is not usually volunteering the second.
The intervals below are our editorial reading of what each assay can realistically detect, drawn from providers' own published guidance and the clock validation literature. They are a position, not a published standard.
| Test family | Realistic retest interval | What can be detected in that window | The trade-off |
|---|---|---|---|
| Glycan / immune age | 6–12 months for a lifestyle change | Sustained change in inflammatory aging | Shorter windows quoted in marketing usually refer to hormonal or drug interventions. Also registers recent illness, injury and training load. |
| Pace-of-aging (DunedinPACE) | 9–12 months | A change in the rate of aging | Reports a rate, so it is the most comparable between your own tests |
| Second-generation clocks (GrimAge, PhenoAge) | 12 months | Large sustained changes only | Best mortality validation; poorest sensitivity to short-term effort |
| First-generation clocks (Horvath, Hannum) | Not worth retesting for this purpose | Little. They were trained to track your birthday. | Accurate at guessing age, which is the wrong target here |
Whichever family you choose, the retest is only interpretable if the conditions match: same provider, same assay version, same approximate time of day and season, and not within a few weeks of illness or vaccination. Two results from different providers are two different measurements, not a trend. The full comparison of the two families is in methylation clock vs immune age, and how to read a biological age report covers which number on the result to weigh first.
Frequently Asked Questions
Which biological age test is best?
There is no single best test, because the four methodologies answer different questions. For tracking whether an intervention is working, a methylation test that reports a pace-of-aging rate is the most defensible choice, since a rate is less distorted by a single noisy baseline. For understanding an inflammatory picture, a glycan-based test reads that more directly. For deciding what to change this month, a standard blood panel interpreted against optimal ranges beats every biological age product on the market and usually costs less. Buy for the question you actually have.
How much does a biological age test cost?
Between $150 and $600 depending on methodology. Biomarker composites are the cheapest at roughly $150–$250, because they run routine markers through a formula. DNA methylation tests cluster at $230–$500. Glycan tests run $300–$500. Broader wellness products that include biological age as one output among many sit at $400–$600. Prices move with promotions and multi-test bundles, so verify before buying — and factor in that a single reading is close to useless without a matched retest, which doubles the real cost.
Is a more expensive biological age test more accurate?
No, not in the way the price difference implies. Cost tracks what the assay costs to run and how much report comes back with it. Methylation arrays and glycan chromatography are more expensive laboratory work than a formula applied to routine blood markers, and above that you are paying for report breadth and sometimes an included interpretation call. Individual-level precision does not follow the price: within-person test-retest variation of 2 to 4 years is a property of the assay and the clock, so two methylation products running a similar array carry similar noise at $230 or at $500. A premium report returns more numbers, each about as uncertain as the one number a cheaper test returns. The two features that genuinely narrow what you can conclude, a published test-retest precision figure and a pace-of-aging clock, are available at several price points.
Are at-home biological age test kits accurate?
The assays are run in certified laboratories and are accurate at what they measure. The problem is not measurement accuracy but individual-level precision: test-retest variation on the same person from the same sample is often 2–4 years, which is the same magnitude as a year of serious lifestyle change. So the lab is not making an error when two readings differ by three years — that spread is inherent to the method. This is why a single reading should never be treated as a result, and why cross-vendor comparison is meaningless.
Why do two biological age tests give me different ages?
Because they were trained on different outcomes using different biology. A methylation clock reads chemical tags on DNA; a composite runs a formula over blood markers; a glycan test reads sugar structures on antibodies. Even two methylation tests disagree if one runs a first-generation clock trained to predict calendar age and the other runs a second-generation clock trained to predict mortality. A 6–10 year spread between vendors is normal and does not mean either laboratory is wrong.
Is a free biological age quiz worth anything?
As a prompt, yes. As a measurement, no. A free questionnaire estimates your age from self-reported habits — exercise, smoking, sleep, diet — which means it is calculating what its designers believe those habits do to aging, not measuring anything about you. If it tells you that you are aging faster because you sleep five hours and do not train, it has restated your inputs. That can still be useful motivationally. It is not a substitute for a measurement, and it should never be compared against a laboratory result.
What should I buy before a biological age test?
A standard blood panel, read against optimal rather than merely normal ranges. Fasting insulin, apoB, HbA1c, hs-CRP, and a lipid panel typically cost less than any biological age product, are interpretable by any physician, and each points at a specific intervention. A biological age score aggregates that kind of information into one number and in doing so discards the part that tells you what to do. Buy the actionable data first; buy the aggregate score afterwards, if at all.
How often should I retest?
No more than once every 9–12 months, under matched conditions. Same provider, same collection type, same time of day, same fasting state — and not within two weeks of an illness, vaccination, hard training block, or a stretch of poor sleep. Quarterly retesting mostly measures the random state of your week, because within-person noise of 2–4 years swamps the real change a quarter produces. Anyone selling a 90-day retest cycle is selling you your own measurement noise.
How do I check whether a specific test has real evidence behind it?
Open the vendor's science or publications page and ask one question of each citation: does this paper test the product being sold, or does it establish the general methodology? Both kinds are common, and only the first supports a claim about the number you will receive. Then check three things the marketing rarely leads with: whether a test-retest precision figure is published, so you know how large a change has to be before it means anything; which clock generation the product runs, since a first-generation clock trained to predict calendar age cannot support a claim about aging faster than the calendar; and whether interpretation is included at the sticker price or sold as a follow-up consultation. A sample report, which most vendors publish, answers the last one in a couple of minutes.
Do biological age tests actually predict anything?
At the population level, yes — second-generation methylation clocks predict mortality across large cohorts better than chronological age alone does, which is a genuine scientific result. At the individual level the picture is weaker, because the within-person noise is large relative to the between-person signal a single reading carries. The accurate framing is that these tests measure something real about population aging and report it with individual-level precision that is not yet good enough to guide a personal decision on its own.
Related
- Biological age hub — the four methodologies compared
- Methylation clock vs immune age — the two test families
- How to read a biological age report
- What is biological age — what a clock actually reads
- How to lower biological age — ranked by evidence
- Elysium review
- TruDiagnostic review
- Normal vs optimal ranges — the panel worth running first