IPM Calculator (Feed Rate)

Formula and worked example

Formula

Milling: IPM = IPT × flutes × RPM
Turning: IPM = IPR × RPM

Example

0.003 IPT × 4 flutes × 2,387 RPM = 28.64 IPM.

Frequently asked questions

What is the IPM feed-rate formula?

For milling, IPM equals chip load in inches per tooth multiplied by the number of cutting flutes and spindle RPM. Use effective cutting edges rather than counting non-cutting features. For turning, multiply feed per revolution in IPR by spindle RPM.

How do I convert IPR to IPM?

Multiply inches per revolution by spindle RPM. For example, 0.006 IPR at 2,000 RPM equals 12 IPM. This conversion is common in turning, boring, and drilling when a control or process sheet expresses feed in a different unit.

Can I calculate IPM from SFM?

First convert SFM and tool diameter to RPM, then multiply that RPM by chip load and the number of flutes. SFM alone is not enough to determine feed rate because diameter, tooth count, and the intended chip load all affect the resulting IPM.