### Speeds and Feeds Calculator - Good Calculators

The Speeds and Feeds Calculator uses the following formulas: RPM = (12 * Surface Speed) / (PI * Tool Diameter) [revs/min] Feed Rate = RPM * Chip Load * Number of Teeth (Flutes) [in/min] Where PI is the constant (3.141592654). Reference: Erik Oberg, et.al. (2008). Machinery's Handbook. 28th .