Calmagite is primarily used as a complexometric indicator in analytical chemistry, particularly in the titration of calcium and magnesium ions in water hardness testing. When added to a solution containing these ions, it forms a distinct color change, typically from red to blue, signaling the endpoint of the titration. This makes it a valuable tool in environmental and industrial applications where monitoring water quality is essential. Additionally, it is utilized in biochemical research for studying metal ion interactions in biological systems. Its sensitivity to specific metal ions ensures accurate and reliable results in various analytical procedures.