Speeds for the Lathe and Mill

Given the SFM, what RPM should be used

This calculator returns the RPM (revolutions per minute) for a given SFM (surface feet per minute) entered. There is a simple formula for these calculations:

RPM = \frac{3.82 \times SFM}{Diameter}

To use the calculator simply enter the SFM desired and the diameter of your part (for lathe work) or the diameter of your milling cutter (for milling). The following table displays some common SFM recommendations.

Material	Recommended SFM (HSS)	Recommended SFM (Carbide)
Mild steel	90	180
Tool steel	50	100
Aluminum & brass	150	300
Bronze	100	200
Stainless steel	40	80

Enter the following data: Diameter of Work or Cutter
Desired SFM
If Milling Enter Number of Flutes (or inserts)

RPM =

It is recommended that you select an RPM that is less than or equal to that shown above.