As the use of computer numerical control (CNC) turning machines continues to grow in popularity across different industries, it has become increasingly essential to possess advanced technical knowledge in operating and manipulating these machines. One crucial aspect of CNC turning that is often overlooked, yet critical, is understanding how to calculate the rotation per minute (RPM) of the spindle. RPM is a fundamental measurement that determines the cutting speed, feed rate, and the desired quality of the machined component. In this guide, we will provide a comprehensive approach to calculating RPM in CNC turning.