In the competitive world, an organization can sustain in its business if its human resources are well maintained and utilized. Workforces are trained and made them fit to work in the organization. Their knowledge is used to get the desired result for the benefit of the organization. So, the knowledge gained by the workforce during their stay in the organization has got equal importance as compared to the profit the organization looking for. The knowledge that has been gained during the tenure of an employee in the organization is lost from the day he/she separates from the organization. The purpose of this paper is to establish that knowledge loss can be calculated in quantitative terms apart from qualitative statements and these quantitative terms of knowledge loss may help organizations for strategic decision on retention of knowledge through better understanding and visualization of loss. The study made in one of the units of a public sector organization in India having nine operative units across the country. This is an exploratory nature of case study, conducted open-ended interview. Primary data were collected from HR department and face to face interview with senior managers. Analysis done based on data collected and measurement of knowledge loss calculated. This paper established that knowledge loss can be calculated in quantitative terms using some formula based on certain data with respect to the employee in the organization in respective position.