Spindle Speed Calculator
Convert between Surface Feet per Minute (SFM) and Revolutions per Minute (RPM).
Required RPM
The Math
Surface Feet per Minute (SFM) is provided by the tooling manufacturer based on the material being cut. This formula calculates the necessary spindle speed (RPM).
RPM = (SFM × 3.82) / Diameter
Note: The constant 3.82 is derived from 12 / π (to convert inches to feet).