How we get to a number.
The reference line
Your chronological age sets the baseline. Every marker then moves you above or below that line in years, and the sum of those movements is your biological age.
Marker weighting
Weights are drawn from the effect sizes reported in phenotypic-age and pace-of-aging literature — sleep duration, quality and rhythm, daily walking and sitting time, aerobic and strength activity, stair-climbing breathlessness, vegetable intake, ultra-processed food, sugary drinks, late eating, alcohol, nicotine, everyday stress, social contact and waistline trend.
Amplitude by age
The same load costs an older body more. Marker effects are scaled by an amplitude factor that rises gently with chronological age.
Pace of aging
Your aging speed expresses the same signal as a rate: how many biological years you accumulate per calendar year. 1.00x is on-curve. Below 1.00x you are pulling ahead of your cohort.
What this is not
AgeRewind is not an epigenetic clock and not a medical diagnosis. It is a well-calibrated estimate from self-reported and wearable-grade inputs, intended to show you which behaviours carry the most weight.