Biological age tests: what to measure and how to choose a method
Two people, both 50. In one, the cells match those of a 35-year-old; in the other, a 65-year-old. Their chronological age is identical, but their biological age is not. Let's break down what biological-age tests measure, how DNA methylation works, and how to choose a method that fits your goal.
Biological age is not the same as the number on your ID
Picture two cars of the same model year. The first has driven 50,000 km on smooth highways with regular servicing. The second has racked up 300,000 km on dirt roads, with an oil change once every five years. Same year of manufacture, wildly different condition. It's the same story with people: chronological age is just a counter of the years you've lived, while biological age reflects the real state of your cells, tissues, and organs.
Both people are 50 on paper, but their biological age differs by 30 years. And unlike chronological age, that's the number you can change.
Epigenetics and DNA methylation — the gold standard
Epigenetics is the science of how lifestyle and environment control gene activity without changing the DNA sequence itself. Think of DNA as a book: epigenetics decides which pages are "open" and which are "closed" in each cell.
The key mechanism is DNA methylation: chemical groups (CH₃) attach to stretches of DNA and regulate whether a gene is read. The pattern of these marks changes predictably with age — forming a kind of biomolecular timestamp. In 2013, Steve Horvath at UCLA analyzed roughly 8,000 tissue samples and built the epigenetic clock — an algorithm that predicts biological age from methylation. More accurate versions have followed since: GrimAge (which tracks mortality), PhenoAge, and DunedinPACE (which measures the pace of aging).
One crucial property of epigenetic marks: they are reversible. Unlike genetic mutations, methylation patterns are dynamic and respond to lifestyle. That makes the test more than a diagnosis — it's a tool for tracking progress. Other aging markers round out the picture: telomeres, the state of your mitochondria, and stem-cell function.
Why measure biological age
Routine blood work tells you what's happening right now. Biological age tells you where you're headed. Five reasons to take the measurement. You can start without any lab work — with an estimated biological age from body measurements or a fitness age based on your physical condition.
Many diseases develop for decades with no obvious signs. Biological age flags risk years before symptoms appear — while you can still act preventively instead of reacting to a crisis.
Not everyone ages the same way. The test shows which of your body's systems need support — and lets you direct your effort where it will pay off most.
Epigenetic clocks are among the most thoroughly validated biomarkers of aging. Hundreds of peer-reviewed studies link methylation to mortality and disease.
Changed your diet, started training, fixed your sleep? A repeat test in 6–12 months shows how far your biological age has shifted in the right direction. It's not a feeling — it's a number.
Knowing your biological age turns you from a passive patient into an active participant: you understand where you stand, you see the target, and you track the trend.
6 methods for testing biological age
The approaches differ fundamentally: some analyze DNA methylation and produce a genetic portrait of aging, others look at blood biomarkers or inflammation through glycan analysis, and still others aggregate data from wearables using deep-learning algorithms. You can estimate your biological age from blood right now — in the Bortz Blood Age calculator built on 22 biomarkers.
| Method | DNA methylation | Multiple organs | Inflammation | Standard biomarkers | Sample collection |
|---|---|---|---|---|---|
| SystemAge | ✓ | ✓ 19 | — | — | drop of blood |
| TruDiagnostic | ✓ | ✓ 11 | — | — | drop of blood |
| Function Health | — | — | — | ✓ 100+ | blood panel |
| Tally Health | ✓ | — | — | — | cheek swab |
| GlycanAge | — | — | ✓ | — | drop of blood |
| Superpower | — | — | ◐ | ◐ | app |
How to choose the right test
There's no single "best" test — the right choice depends on your goals, your budget, and exactly what you want to learn about your biological age. Here are some practical pointers.
Go for simplicity and accessibility. A cheek swab or a basic blood panel captures a "baseline" with minimal effort — the point is to get a starting number you can build from.
Choose DNA-methylation tests that cover several organ systems (SystemAge, TruDiagnostic) — they give the most complete picture using the most validated methods.
Look at change-detection accuracy — the higher the percentage, the more confidently a test will reflect the results of your effort. Retest 6–12 months after a lifestyle change.
If chronic inflammation as a driver of aging is your focus, glycan analysis (GlycanAge) offers a unique angle — especially with autoimmune conditions and metabolic syndrome.
Your biological age isn't something you inherited. It's something you build every day, with your choices.calculate Tool · biological age PhenoAge calculator Estimate your biological age from 9 blood markers — free, built on the validated Levine 2018 model, with a breakdown of each marker's contribution. Open the calculator
