# Surface Speed Calculator

**Results**

The surface speed calculator helps you calculate the surface speed by using the stock diameter and rotations per minute.

Enter the stock diameter in inches and RPM to calculate the surface speed in inches per minute, ft per minute, ft per second, and meters per second.

In case you do not know,

In machining, a stock’s spindle speed is called its surface speed, or SFM.

This unit converts spindle rotation into stock speed, which is used to calculate feed rates and other cutting parameters.

The formula of the surface speed is:

SFM = pi x D x RPM

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