This paper provides updated documentation of the Stockpile Sizing Module (SSM), a mathematical model, with associated computer program, that constitutes a key portion of the Risk Assessment and Mitigation Framework for Strategic Materials (RAMF-SM). Developed by the Institute for Defense Analyses, RAMF-SM has played a key role in the analyses that have supported the Reports to the Congress from the Department of Defense concerning requirements for the National Defense Stockpile of strategic and critical non-fuel materials (S&CMs). The SSM estimates shortfalls of S&CMs that might occur in a national emergency scenario. This paper focuses on training a user to set up runs of the SSM computer program and to interpret its output. Detailed descriptions of the model’s inputs and outputs are provided, along with discussion of the underlying methodology.