Reference guide · 2026
Epigenetic clocks, GrimAge, DunedinPACE, GlycanAge, telomere length — what each biological age test actually measures, how accurate it is, and which one to order for your patient or your own longevity panel.
This page is a primer. The full 203-page reference — Diagnostic Tests for Biological Aging — walks through 14 chapters of testing methodology, pre-analytics, CLSI-aligned validation, and interpretation.
See the book — from $24.99A biological age test estimates how old your body is biologically — based on cellular, molecular, or epigenetic biomarkers — rather than your chronological birthdate. The most validated tests today are DNA-methylation 'epigenetic clocks' such as Horvath, Hannum, PhenoAge, GrimAge, and DunedinPACE.
Accuracy depends on the clock. Horvath's 2013 multi-tissue clock correlates with chronological age at r ≈ 0.96 but predicts mortality weakly. GrimAge strongly predicts time-to-death (HR ~1.10 per year of age acceleration). DunedinPACE has the lowest test-retest noise. Telomere length has high biological noise and modest standalone value.
Most consumer biological age tests use a saliva or finger-prick blood sample mailed to a CLIA-certified lab. The lab runs DNA methylation profiling on an Illumina array, then applies a published clock algorithm. Turnaround is typically 3–6 weeks.
There is no single 'best' — it depends on intent. For tracking response to interventions, DunedinPACE has the best test-retest reproducibility. For mortality and disease risk, GrimAge has the strongest peer-reviewed evidence. For research, the original Horvath clock remains the standard reference.
Commercial epigenetic age tests range from $200 (basic methylation panel) to $500+ (full GrimAge/DunedinPACE panel). GlycanAge sits around $250. Telomere length tests are $80–$200. Our reference book details pricing, methodology, and turnaround for each major commercial offering.
Diagnostic Tests for Biological Aging — 203 pages, 14 chapters, 336 references. Written for clinicians, lab scientists, longevity-clinic staff, and graduate students. 5 tiers from $24.99; multi-seat bundles for clinics and labs.
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