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