How to use the drill RPM and feed calculator
Guessing at drill speed is how you burn up a bit or open a hole oversize. Pick the drill diameter and the material and this tool returns the spindle speed, the feed rate in inches per minute, a suggested feed window for that diameter, and the time it takes to push through one hole.
Speed comes from surface footage, not from the drill size alone. The tool applies RPM = 12 x SFM / (pi x D), the same relation shops shorten to 3.82 x SFM / D. Drilling mild steel at 90 SFM with a 1/4 in high speed steel drill gives about 1,375 RPM, and multiplying by the feed per revolution gives the IPM feed.
The preset surface speeds describe high speed steel drills. Solid carbide and coated drills run two to three times faster, while poor coolant delivery or deep holes call for lower numbers. Stainless and titanium work harden quickly, so keeping a steady positive feed matters more than pushing the RPM up.
Time per hole is the material thickness plus the drill point cone allowance divided by the feed rate. Once hole depth passes about three diameters chip evacuation becomes the limiting factor, so consider peck drilling or a through-coolant drill and start below the calculated feed.
Frequently asked questions
Pick the surface speed in SFM for the material, then use RPM = 3.82 x SFM / drill diameter in inches. The presets here are high speed steel figures, and solid carbide drills can run two to three times faster.
Feed scales with drill diameter. Roughly 0.002 to 0.004 IPR for 1/8 to 1/4 in drills and 0.004 to 0.007 IPR for 1/4 to 1/2 in drills, reduced for deep holes so chips can clear.