Definition. This chart presents the average lifespan held per coin — the age of the average HODL wave — shown alongside Coin Days Destroyed (orange), Circulating Supply (blue) and price (grey). It is based upon the following principles:

• Lifespan is a measurement of either the time since a coin was last moved (unspent coins), or the expended time when a coin is moved (spent coins).

• Each unit of coin in the supply creates an equivalent volume of coindays per day.

• Some portion of the coin supply is spent each day, destroying the accumulated coindays (called Coindays Destroyed, CDD).

Technical. The remaining non-destroyed coindays are aggregated, and then divided by the Circulating Supply to obtain the average lifespan per coin, expressed in days:

• Average Lifespan per Coin = cumsum(Circulating Supply - CDD) / Circulating Supply

Interpretation. The average lifespan rises when the supply accumulates coindays faster than they are destroyed — the signature of dominant HODLing behavior and a maturing, increasingly dormant coin supply. It flattens or declines when large volumes of old coins are spent, destroying their accumulated lifespan in the process, which is characteristic of distribution phases and periods of elevated on-chain turnover. Because the measure is cumulative, it moves slowly and is best read as a macro gauge of holding behavior rather than a short-term signal.

Notes. Built from Coin Days Destroyed and Circulating Supply. The cumulative ratio counterpart of this concept — coindays destroyed relative to all coindays ever accumulated — is charted by Liveliness.