Purpose: This paper seeks to propose and discuss a knowledge management tool which has been designed to enable small to medium-sized enterprises (SMEs) to obtain information about the concentration of relevant knowledge with certain individuals respectively in certain departments. Design/methodology/approach: The tool represents an outcome of the authors' ongoing research activities related to the danger of knowledge loss due to turnover or long-term absence. A static knowledge map was developed based on a series of semi-structured interviews with 14 organization members from a German medium-sized enterprise operating in the printing sector. To apply this knowledge map to a broader range of SMEs a knowledge management tool has been developed. As underlying framework, the IC classification scheme and the concept of social capital were utilized. Findings: The knowledge management tool helps smaller firms to calculate a "knowledge at risk" score, which gives them a better understanding of their critical organization members and what is making them critical. Practical implications: The tool's outcome can illustrate the potential danger of organizational turnover, which hopefully triggers the development and implementation of specific replacement/retention measures in a timely manner. Originality/value: A tool is proposed that identifies indispensable organization members within SMEs. The tool's strength is its simple but powerful nature which does not require long-term preparation and/or training.