End Mill Speed and Feed Calculator

MILLING

Get RPM and feed rate for an end mill in one step from diameter, target SFM, flute count, and chip load.

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Spindle Speed (RPM)
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Feed Rate (IPM)

RPM = (SFM x 3.82) / D. Feed = RPM x Chip Load x Flutes. Treat as a starting point and adjust for rigidity, overhang, and finish requirements.

How it works

This combines the two most common shop-floor lookups, spindle speed from surface speed, and feed rate from chip load, into a single pass so an end mill setup is one calculation instead of two.

FAQ

Why does my feed look low? Small-diameter, high-flute-count end mills often need feed rates that surprise people; trust the chip load number over intuition.

Related Guides

CNC Calculators · SFM Calculator · Chip Load Calculator

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The calculators and tools on Formula Factory are provided for general guidance and informational purposes only. Results are estimates based on standard formulas and the values you enter — they do not constitute professional engineering, electrical, or architectural advice. Always verify calculations with a qualified professional before making decisions for any safety-critical, code-compliance, or commercial application. Formula Factory makes no representations or warranties as to the accuracy or completeness of any result, and accepts no liability for errors, omissions, or any outcomes arising from reliance on this information.