<p>Growing interest in attributing a monetary value to psychological health at work has led to suggestions that a standardized methodology needs to be developed to provide valid monetary estimates at the desired level of investigation. Currently, there is no valid methodology for calculating the cost of employees’ psychological health at the organizational level even though such monetary estimates can provide an economic justification for organizational investments targeting employees’ psychological health. In addition, most, if not all current methodologies attempt to attribute a monetary cost to poor psychological health but fail to consider the possibility of a monetary gain being attributable to great psychological health. Lastly, current methodologies are limited by their inability to consider multiple indicators of psychological health (e.g., burnout and engagement) and organizational costs (e.g., absenteeism and presenteeism) simultaneously. We seek to address these gaps by presenting a methodology, the Psychological Gain Calculator (PGC), that allows researchers and practitioners to estimate how much money an organization stands to gain by helping employees with poor psychological health and by maintaining good psychological health for employees who have it. From a business standpoint, estimating organizational costs attributable to psychological health presents an economic justification to invest in employee well-being while guiding the scope of these investments. We provide a demonstration of the PGC using survey data obtained from a mid-to-large-size Canadian public service organization and report on the monetary estimates attributable to psychological health in this organization.</p>