Drill Speed and Feed Calculator

DRILLING

Get spindle speed and feed rate for a twist drill from diameter, target surface speed, and feed per revolution.

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Spindle Speed (RPM)
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Feed Rate (in/min)

RPM = (SFM x 3.82) / D. Feed rate = RPM x feed per revolution. Drills feed per revolution, not per tooth, since both flutes engage together.

How it works

Twist drills run slower surface speeds than end mills because the chisel edge at the tip does not cut cleanly, it scrapes. Starting from a conservative SFM for the material and converting straight to RPM and feed keeps the drill from burning up on entry.

FAQ

Why is drill SFM lower than milling SFM for the same material? The center of a twist drill does not have a true cutting edge, so the whole tool runs slower to protect that chisel point.

Related Guides

CNC Calculators · SFM Calculator · Peck Drilling 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.