Drill Feed and Speed Calculator
This drill feed and speed calculator is built specifically for drilling, not retuned from a mill calculator. Drill SFM is about 25 percent slower than end-mill SFM in the same material, and drill feed is specified in inches per revolution (IPR) rather than per tooth. Enter drill diameter, material, and HSS or carbide, and the calculator returns spindle RPM, feed per revolution, feed rate in inches per minute, a safe peck depth, and dwell time for blind holes.
Drill feed and speed equations
The drill speed and feed calculator math is two equations:
- RPM = (SFM x 12) / (pi x D) where SFM is the drilling cutting speed and D is the drill diameter in inches.
- Feed rate (IPM) = RPM x IPR where IPR is the feed per revolution, typically 0.001-0.015 IPR depending on drill size and material.
For a 1/4 inch HSS drill in mild steel at 80 SFM: RPM = (80 x 12) / (pi x 0.25) = 1,222 RPM. At 0.0045 IPR (0.018 per inch of diameter x 0.25), feed rate = 1,222 x 0.0045 = 5.5 IPM.
Drill SFM reference
| Material | HSS drill SFM | Carbide drill SFM |
|---|---|---|
| Aluminum | 300 | 800 |
| Mild steel (1018) | 80 | 250 |
| Alloy steel (4140) | 60 | 180 |
| Stainless steel | 40 | 130 |
| Cast iron | 60 | 200 |
| Titanium | 25 | 80 |
| Brass | 200 | 400 |
| Plastic | 400 | 1000 |
Peck drilling and dwell
For through holes up to about 3x diameter, drill straight through. For blind holes, add a 0.5 to 1.0 second dwell at depth to clean up the bottom before retract. For deep holes over 5x diameter, peck-drill with a peck depth of about 1x drill diameter (less in titanium and stainless where chips weld to the flutes). The drill feed and speed calculator returns a peck depth that reflects material and hole type.
Drill feed and speed vs mill feed and speed
A drill speed and feed calculator is not the same as a mill feed and speed calculator. Drills run lower SFM because chip evacuation is harder at the tip and coolant cannot reach the cutting edge directly. Drills also feed in IPR (the chip thickness per revolution) rather than IPM per tooth. Use this drill feed and speed calculator for any drilling operation; use the feeds and speeds calculator for milling.