RPM to Surface Speed Converter
Convert between RPM and surface speed (SFM, m/min) based on diameter.
Enter RPM and diameter for instant surface speed calculation.
Enter RPM and diameter — see surface speed instantly.
Surface speed depends on both RPM and the diameter of the rotating part.
Formulas:
- SFM = RPM x Pi x Diameter (inches) / 12
- m/min = RPM x Pi x Diameter (mm) / 1000
- RPM = SFM x 12 / (Pi x Diameter in inches)
SFM = Surface Feet per Minute (used in US machining) m/min = Meters per minute (used in metric machining)
Common cutting speeds (SFM):
- Mild steel with HSS: 60-100 SFM
- Aluminum with HSS: 200-300 SFM
- Mild steel with carbide: 300-500 SFM
- Aluminum with carbide: 800-1200 SFM
Example:
- Turning a 2-inch diameter bar at 500 RPM:
- SFM = 500 x 3.14159 x 2 / 12 = 262 SFM