Drill Speed & Feed Calculator
Use this calculator to estimate spindle RPM and feed rate for twist drilling operations. Choose units, material, and your drill data to get recommended starting values.
Why speed and feed matter in drilling
Drilling performance depends heavily on choosing a reasonable spindle speed and feed rate. Too much speed causes heat, early tool wear, poor hole finish, and sometimes work hardening in stainless alloys. Too little feed can rub rather than cut, which also generates heat and shortens tool life.
A practical setup balances three things:
- Tool life: Avoid overheating and excessive edge wear.
- Productivity: Remove material quickly without chatter or tool breakage.
- Hole quality: Achieve acceptable diameter, straightness, and surface finish.
Core formulas used by the calculator
Imperial (inch):
RPM = (SFM × 12) / (π × Drill Diameter in inches)
Metric (mm):
RPM = (Cutting Speed m/min × 1000) / (π × Drill Diameter in mm)
Feed Rate:
Feed Rate = RPM × Feed per Revolution
The calculator also applies your machine/setup factor to provide a practical adjusted RPM and adjusted feed rate.
How to use this drill speed feed calculator
1) Select units
Choose Imperial if your shop works in inch and SFM. Choose Metric for mm and m/min workflows.
2) Pick a material preset (or custom)
Presets fill common starting values for HSS drilling. If you have manufacturer data for carbide or coated tools, choose custom and enter those values directly.
3) Enter drill diameter, cutting speed, and feed/rev
Diameter has a strong effect on RPM. Smaller drills require much higher RPM at the same surface speed.
4) Add hole depth for time estimate
If depth is entered, the calculator estimates drilling time from feed rate (not including retract, peck cycles, or tool changes).
Starting reference values (HSS drills)
| Material | Speed (SFM) | Speed (m/min) | Feed/Rev (in/rev) | Feed/Rev (mm/rev) |
|---|---|---|---|---|
| Mild Steel | 80 | 25 | 0.004 | 0.10 |
| Stainless Steel | 50 | 15 | 0.003 | 0.08 |
| Aluminum | 250 | 75 | 0.006 | 0.15 |
| Brass | 200 | 60 | 0.005 | 0.13 |
| Cast Iron | 70 | 22 | 0.004 | 0.10 |
| Titanium | 30 | 10 | 0.002 | 0.05 |
Practical tips for better drilling results
- Center drill or spot drill before deep or precise holes.
- Use peck drilling for deep holes and poor chip evacuation conditions.
- Use coolant/lubrication appropriate to material and machine type.
- Reduce speed for interrupted cuts, hard skin, or unstable setups.
- Increase feed slightly if the drill is rubbing instead of cutting.
- For small drills, verify spindle can actually reach required RPM.
Common mistakes to avoid
Running too fast in hard materials
This often causes thermal damage at the cutting edge and sudden wear.
Using ultra-low feed to “be safe”
Very low feed can be unsafe for tool life because it rubs and work-hardens the material.
Ignoring tool manufacturer data
Always prioritize manufacturer recommendations when available. This calculator is a fast planning tool, not a substitute for process qualification.
Final notes
A solid drilling process starts with sound estimates and then improves through observation: chip shape, spindle load, vibration, hole finish, and tool wear pattern. Use the calculator to get in the right zone quickly, then fine-tune in small increments for your machine and part requirements.