Drill Feed and Speed Calculator
Whether you operate a CNC machine or use manual equipment, setting the correct feed and speed is critical for clean holes and long tool life. Our drill feed and speed calculator is built specifically for drilling operations. Simply enter your drill diameter, workpiece material, and tool material (High-Speed Steel or Carbide). We will instantly calculate your optimal spindle RPM, feed per revolution (IPR), feed rate (IPM), safe peck depth, and dwell time.
A Dedicated Tool for Drilling
This tool is not just a modified milling calculator. Drilling requires a unique approach because chip evacuation is harder at the tip, and coolant cannot easily reach the cutting edge deep inside a hole. As a result, drill Surface Feet per Minute (SFM) runs about 25% slower than end-mill SFM in the exact same material. Additionally, drill feed rates use inches per revolution (IPR) rather than inches per minute per tooth.
The Core Feed and Speed Equations
Our calculator relies on two primary formulas to determine your ideal machine settings:
RPM = (SFM x 12) / (π x D)
- SFM is your cutting speed.
- D is your drill diameter in inches.
Feed Rate (IPM) = RPM x IPR
- IPR is your feed per revolution, which usually ranges from 0.001 to 0.015 depending on the material and drill size.
Example Calculation:
If you use a 1/4-inch HSS drill on mild steel at 80 SFM, your calculation is (80 x 12) / (3.14 x 0.25). This gives you a spindle speed of 1,222 RPM. At a feed rate of 0.0045 IPR, your final feed rate is 5.5 IPM (1,222 x 0.0045).
Standard SFM Reference Chart
Different materials require completely different cutting speeds. Here are the baseline SFM speeds our calculator uses:
| Workpiece Material | HSS Drill SFM | Carbide Drill SFM |
|---|---|---|
| Aluminum | 300 | 800 |
| Plastic | 400 | 1,000 |
| Brass | 200 | 400 |
| Mild Steel (1018) | 80 | 250 |
| Alloy Steel (4140) | 60 | 180 |
| Cast Iron | 60 | 200 |
| Stainless Steel | 40 | 130 |
| Titanium | 25 | 80 |
Peck Drilling and Dwell Times
The depth of your hole dictates how you should run the drill:
- Shallow Through Holes: For holes up to three times your drill diameter, you can usually drill straight through without stopping.
- Blind Holes: If the hole does not go all the way through the material, program a 0.5- to 1.0-second dwell at the bottom. This brief pause cleans up the bottom of the hole before the drill retracts.
- Deep Holes: For holes deeper than five times your drill diameter, you must peck-drill. A standard peck depth equals one drill diameter. You should reduce this peck depth further when working with sticky materials like titanium and stainless steel, as chips easily weld to the drill flutes.
Drilling vs. Milling Calculations
Never use a milling calculator to set up a drilling operation. Drills always run at a lower SFM than end mills to prevent the tool from overheating deep inside the workpiece. Drills also measure feed rates in IPR, which indicates the actual chip thickness created during one full revolution. Use this calculator for all your drilling needs, and use a dedicated milling calculator for your end-mill operations.