Risk Priority Number (RPN) is a measure used when assessing risk to help identify critical failure modes associated with your design or process. The RPN values range from 1 (absolute best) to 1000 (absolute worst). The FMEA RPN is commonly used in the automotive industry and it is somewhat similar to the criticality numbers used in Mil-Std-1629A. The graphic below shows the factors that make up the RPN and how it is calculated for each failure mode.