Supply Retention Rate is a supply-weighted cohort survival curve: the fraction of today's circulating supply that already existed h days ago and has not moved since, R_h(t) = (share of supply aged ≥ h today) × supply(t) / supply(t − h).

The HODL Waves published elsewhere on this site show the cross-sectional age distribution of the supply at a single point in time. This chart transposes that into a true survival rate: it divides by the supply that actually existed h days ago, so it answers "of the coins that existed back then, what fraction is still unmoved" rather than "what fraction of today's supply is old" — the same distinction between a population pyramid and a cohort retention curve in demographic analysis.

Age resets on any spend, including self-custody consolidations, so R_h is a lower bound on true holder retention — a limitation shared with the whole coin-age metric family (CDD, Liveliness, Dormancy). See the Holder Conviction Index for a single composite score built on top of this curve.