Drill speed without the guesswork
Run a drill too fast and the lips burn and dull in seconds; too slow and it grabs and walks. The right spindle speed comes straight from the drill diameter and the material cutting speed, and the right feed comes from how far the drill should advance each revolution. This calculator gives you both at once for the drill press or mill.
The formulas
Spindle speed: RPM = (SFM x 12) / (pi x D) in imperial, or RPM = (Vc x 1000) / (pi x D) in metric, with D the drill diameter. Feed rate = RPM x feed per revolution. Drills are fed per revolution, not per tooth, because both lips share the cut.
Where these fit in speeds and feeds
This tool bundles the spindle-speed step from the RPM calculator with a drilling feed. For milling, where you feed per tooth across multiple flutes, use the feed rate calculator instead.
Typical drilling speeds (HSS)
| Material | Cutting speed (SFM) | Feed per rev (in) |
|---|---|---|
| Aluminum | 200 – 300 | 0.004 – 0.010 |
| Brass | 120 – 200 | 0.004 – 0.010 |
| Mild steel | 80 – 110 | 0.003 – 0.008 |
| Cast iron | 70 – 100 | 0.004 – 0.010 |
| Stainless steel | 30 – 50 | 0.002 – 0.005 |
Carbide drills run roughly two to three times these speeds. Feed per revolution rises with drill diameter — bigger drills take a bigger bite.
Worked example
A 1/4 inch HSS drill in mild steel at 100 SFM: RPM = (100 x 12) / (pi x 0.25) = 1528 RPM, and at 0.005 in/rev the feed is about 7.6 IPM.
FAQ
Why does a smaller drill spin faster?
Surface speed is fixed by the material, and a smaller diameter covers less distance per turn, so it must spin faster to reach the same edge speed. That is why tiny drills need very high RPM.
Should I peck drill?
For deep holes past about three diameters, peck to clear chips and let coolant reach the tip. It does not change the speed, just how you apply the feed.