How accurate are epigenetic tests?
Read DNA methylation from saliva or blood. Horvath, PhenoAge and GrimAge are the best-known clocks. Accuracy is high, but a single reading is noisy — retest at 6-12 month intervals.
How do blood-panel formulas estimate biological age?
PhenoAge uses nine routine values: albumin, creatinine, glucose, CRP, lymphocyte percentage, MCV, RDW, alkaline phosphatase and white cell count. Cheap if you already do annual bloodwork.
Which functional tests can you do at home?
Resting heart rate: 60 seconds before getting out of bed; 50-65 signals good conditioning.
Sit-to-stand: rising from the floor without hands measures mobility and lower-body strength.
Single-leg balance: ten seconds or more, eyes open, predicts fall risk later in life.
Four flights of stairs without stopping is a practical fitness threshold.
Does estimation from daily behaviour work?
Sleep regularity, steps, stress and activity intensity can produce an age estimate with no lab at all. Less precise than an epigenetic clock, but far more effective at changing behaviour because feedback is daily.
fjt sits in this category: a 30-second daily check-in plus phone step data.
