The Gray to Green (G2G) decision support tool is a GIS-based toolkit that guides users in transitioning to vegetation-based (green) stormwater management systems designed to slow, spread, soak, and manage stormwater as a valuable resource for people and the environment. G2G utilizes GIS to help users identify potential areas for protecting and restoring green infrastructure and siting 11 low impact development (LID) best management practices. It utilizes Excel to help users quantify water volume and pollutant load reductions as well as other benefits for different development scenarios. The strength of G2G is the scenario testing which allows users to see what happens when you maximize the use of green infrastructure and LID practices. It expands the understanding of what is possible for users both with and without practical experience using LID practices. Although there are very sophisticated models for evaluating stormwater designs, they require special expertise to run and are not easily applied or commonly used for planning, regardless of the scale. Planners, resource managers, scientists, and engineers can use G2G to guide project planning for urban reforestation; new development and redevelopment; stormwater retrofits for water quality enhancement and flood reduction; and community resilience and adaptation to climate change.