Woody detritus or dead wood is an important part of forest ecosystems and has become a routine facet of forest monitoring and inventory. Biomass and carbon estimates of dead wood depend on knowledge of species- and decay class-specific density or density reduction factors. While some progress has been made in determining these parameters for dead or downed trees (DD), there are very few estimates of these key parameters for standing dead trees (SD). We evaluated indicators of decay to relate subjective SD and DD decay classifications then compared SD and DD density and density reduction factors by decay class for a total of 19 tree species at nine sites in the United States and Russia. Results indicate that SD density declined with decay class for all examined species. By applying these results, a new set of SD density reduction factors was developed for 260 species inventoried by the U.S. Forest Service's Forest Inventory and Analysis program in the United States.