The pivotal role of precipitation in driving the terrestrial water cycle is well-known, but quantifying its transformation into terrestrial water storage remains challenging. This study introduces a new metric -- the average daily fraction of precipitation transformed into terrestrial water storage -- leveraging an advanced statistical reconstruction method and data from the Gravity Recovery and Climate Experiment (GRACE) satellites and their follow-on mission. Results show that about 64% of land precipitation contributes to terrestrial water storage across 121 global river basins from 2002 to 2021, with notable variations across climatic and geographical regions. We also analyze changes in this fraction across global mascons. Our findings shed light on the interactions between precipitation, land surface processes, and climate change, providing valuable insights for water resource management and hydrological modeling.