Calculators
Drill Speed & Feed Calculator
Convert a cutting speed (SFM or m/min) and drill diameter into spindle RPM, and a feed per revolution into feed rate (in/min or mm/min) — with typical starting surface speeds by material.
Last verified: 2026-07-09
Drilling speed is set by the material's cutting speed and the drill diameter (RPM), and feed by how far the drill advances per revolution (feed per rev). Enter your numbers below for RPM and feed rate, then use the reference table for a starting cutting speed.
Units
Spindle speed
764 RPM
Feed rate
3.82 in/min
RPM = (cutting speed × K) ÷ (π × Ø); feed rate = RPM × feed-per-rev. Starting points only — always confirm against your tool manufacturer's data, material, machine rigidity, and coolant.
Typical starting cutting speeds
| Material | HSS (SFM) | Carbide (SFM) |
|---|---|---|
| Aluminum alloys | 200–300 | 500–1000+ |
| Brass | 150–250 | 400–600 |
| Mild steel (1018) | 80–100 | 250–400 |
| Alloy steel (4140) | 60–80 | 200–350 |
| Stainless (304) | 40–60 | 150–300 |
| Cast iron | 60–80 | 200–350 |
| Titanium | 30–50 | 100–200 |
- Feed per rev grows with drill size: as a rough start, ~0.001–0.003 in/rev for small drills (<1/8"), ~0.004–0.008 for 1/4"–1/2", more for larger.
- Peck drill deep holes (depth > ~3–4× diameter) to clear chips.
- Reduce speed and use firm feed in stainless and titanium to avoid work-hardening; keep the drill cutting, not rubbing.
Frequently asked
- How is RPM calculated from SFM?
- RPM = (12 × SFM) ÷ (π × diameter in inches), which is about 3.82 × SFM ÷ diameter. In metric, RPM = (1000 × Vc in m/min) ÷ (π × diameter in mm). Smaller drills spin faster for the same surface speed.
- What feed per revolution should I start with?
- It scales with drill diameter — very roughly 0.001–0.003 in/rev for small drills up to 0.004–0.008+ for 1/4"–1/2". Start conservative, watch chip formation (you want chips, not dust or long stringers), and adjust.
- Are these speeds exact?
- No — they're starting points. Real speeds depend on coating, coolant, hole depth, machine rigidity, and drill type. Always cross-check the tool manufacturer's recommendation.
Sources
- Standard machining speed/feed relationships (RPM from surface speed; feed = RPM × feed-per-rev)