Bitcoin Days Destroyed (Bitcoin Days Destroyed, BDD) is a specific measure of network activity that assesses the movement of funds taking into account how long they were held. Unlike a simple count of transaction volume, the metric gives greater weight to coins that remained unmoved for a long time and were then spent.

The calculation principle is simple: the number of bitcoins moved is multiplied by the number of days they remained motionless. For example, if coins lay without operations for a week and were then sent, each of them "destroys" the idle days accumulated over that time. The longer an asset was held before being spent, the greater its contribution to the final value of the indicator.

BDD is used as an indicator of the real economic activity of the network and helps analysts identify moments when long-"dormant" coins start moving. Such events may point to the actions of long-term holders. The metric reduces the influence of frequent movements of small amounts and makes the picture of network activity more meaningful.