Enter the drill diameter (inches) and the RPM into the calculator to determine the drill SFM.

Drill SFM Formula

The following formula is used to calculate a drill’s surface feet per minute (SFM). 

DSFM = .2618 * D * RPM
  • Where DSFM is the drill surface feet per minute
  • D is the diameter of the drill
  • RPM is the rotations per minute of the drill

To calculate the drill SFM, multiply the diameter of the drill by the RPM, then multiply again by .2618.

What is drill SFM?

Definition:

A drill SFM, short for drill surface feet per minute, is a measure of the linear tangential distance the surface of the drill travels per minute of time.

Drill SFM is used to determine proper feed rates and total machine times.

How to calculate drill SFM?

Example Problem:

The following example problem outlines the steps and information needed to calculate a drill’s surface feet per minute (DSFM).

First, determine or measure the diameter of the drill. In this example, the drill is measured to have a diameter of 2.5 inches.

Next, calculate or measure the RPM of the drill. In this case, the drill is rotating at a rate of 1000 rotations per minute.

Finally, calculate the drill SFM using the formula above:

DSFM = .2618 * D * RPM

DSFM = .2618 * 2.5 * 1000

DSFM = 654.5