How to Test Biological Age: Clocks, Blood Panels & Home Tests

When people ask how to test biological age, they usually think of a $300 mail-in saliva or blood-spot kit. In reality, longevity researchers and physicians divide biological age testing into three tiers: functional physiological markers, clinical blood-chemistry clocks (like Levine's PhenoAge), and epigenetic DNA methylation clocks (like Horvath, GrimAge, and DunedinPACE).

If your goal is living longer rather than screenshotting a younger birthday, start with Tier 1 and Tier 2. Functional biomarkers and routine bloodwork directly tell you what to fix (blood pressure, insulin resistance, cardiorespiratory fitness, or muscle mass), whereas a methylation clock only outputs a summary score.

In Peter Attia's Outlive, cardiorespiratory fitness (VO2 max) and muscular strength (grip strength and leg strength) are stronger predictors of 10-year all-cause mortality than any epigenetic saliva kit. You can benchmark functional biological age at home using four tools:

1. Vascular Age & Body Composition: The Withings Body Scan estimates Vascular Age via pulse wave velocity alongside segmental lean mass and visceral fat. 2. Resting Blood Pressure: Track morning and evening readings with the Omron 10 Series BP Monitor (target <120/80 mmHg). 3. Overnight HRV & Resting Heart Rate: Use an Oura Ring Gen 4 or Polar H10 to compare your HRV and RHR against age-decade norms. 4. Grip Strength: Test and train crush grip with IronMind Captains of Crush Grippers.

Before buying an epigenetic kit, run Morgan Levine's PhenoAge formula on your standard annual blood panel. It requires nine routine lab values (albumin, creatinine, fasting glucose, C-reactive protein, lymphocyte percentage, mean cell volume, red cell distribution width, alkaline phosphatase, and white blood cell count) plus chronological age.

If you still want a DNA methylation test, understand clock generations: 1st-generation clocks (Horvath, Hannum) were trained to predict chronological birthday and are noisy for longevity interventions; 2nd-generation clocks (PhenoAge, GrimAge) predict mortality and healthspan; 3rd-generation clocks (DunedinPACE) measure your current speed of aging (how many biological years you age per chronological year).

Buy an epigenetic test only if you already have ApoB, HbA1c, fasting insulin, blood pressure, sleep, and strength training dialed in, and you want a 12-month check on a major protocol change. Retest using the exact same lab under identical conditions (fasted, no acute illness, no hard workout 24 hours prior).

Skip quarterly retests, skip averaging three different clock brands, and never treat a younger biological-age number as permission to ignore high ApoB or elevated blood pressure.