# Drill Feed and Speed Calculator

Drill feed and speed calculator for CNC and manual drilling. Returns spindle RPM, feed per revolution (IPR), feed rate (IPM), peck depth, and dwell time for HSS and carbide drills.

## What this calculates

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.

## Inputs

- **Drill Diameter** (in) — min 0.001 — Drill bit diameter. Cutting speed scales inversely with diameter.
- **Workpiece Material** — options: Aluminum (300/800 SFM), Mild steel / 1018 (80/250 SFM), Alloy steel / 4140 (60/180 SFM), Stainless steel (40/130 SFM), Cast iron (60/200 SFM), Brass (200/400 SFM), Bronze (100/250 SFM), Copper (150/350 SFM), Titanium (25/80 SFM), Plastic (400/1000 SFM) — Material being drilled.
- **Drill Material** — options: HSS (high-speed steel), Solid carbide — HSS is the default for hand-drilling and most small shops. Carbide runs 2-3x faster but chips under interrupted cuts.
- **Hole Type** — options: Through hole, Blind hole, Deep hole (over 5x D) — Deep holes need pecking. Blind holes get a dwell at depth.
- **Hole Depth** (in) — min 0 — Total depth of the hole. Used to compute cycle time and peck count.

## Outputs

- **Spindle Speed** (RPM) — RPM = (SFM x 12) / (pi x D) for drilling.
- **Cutting Speed** (SFM) — Drilling SFM baseline for the material and tool combination.
- **Feed per Revolution** (in/rev) — Feed per revolution scaled to drill diameter.
- **Feed Rate** (in/min) — Linear feed rate = RPM x IPR.
- **Recommended Peck Depth** (in) — Safe peck depth for deep-hole cycles (about 1x drill diameter).
- **Recommended Dwell at Depth** (s) — Dwell time for blind holes to clean up the bottom before retract.
- **Approx Cycle Time** (s) — Approximate time at depth = hole depth / feed rate.

## Details

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

  
    MaterialHSS drill SFMCarbide drill SFM
  
  
    Aluminum300800
    Mild steel (1018)80250
    Alloy steel (4140)60180
    Stainless steel40130
    Cast iron60200
    Titanium2580
    Brass200400
    Plastic4001000
  

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.

## Frequently Asked Questions

**Q: How do I calculate drill feed and speed?**

A: RPM = (SFM x 12) / (pi x D), where SFM is the drilling cutting speed for your material and D is the drill diameter in inches. Then feed rate (IPM) = RPM x IPR, where IPR is the feed per revolution, typically 0.015 IPR per inch of drill diameter in steel. The drill feed and speed calculator does both steps in one entry.

**Q: What speed should I drill mild steel at?**

A: For HSS drills, about 80 SFM. A 1/4 inch HSS drill runs at 1,222 RPM with 0.0045 IPR feed (5.5 IPM). A 1/2 inch HSS drill runs at 611 RPM with 0.009 IPR (5.5 IPM). Carbide drills run 3x faster at 250 SFM.

**Q: Why do drills feed in IPR instead of IPM?**

A: IPR specifies chip thickness per revolution, which is what determines chip formation and drill life. Milling feed is IPM because a mill moves through the work independently of spindle speed. Drill feed rate in IPM is a derived value: IPM = RPM x IPR. A drill speed and feed calculator converts between the two.

**Q: When should I peck-drill?**

A: Peck-drill when hole depth exceeds about 3x drill diameter, or any time chip evacuation is a problem (deep holes, stringy materials, or poor flute geometry). Peck depth is about 1x drill diameter for steel, 0.5x for titanium or stainless. The calculator returns a recommended peck depth based on the material and hole type.

**Q: Do I need different feed and speed for carbide drills?**

A: Yes. Carbide drills run at 2-3x the SFM of HSS drills in the same material, but only if the machine and workholding are rigid. For a flexible setup or interrupted cut, stay with HSS. Carbide drills chip under shock load. The calculator has separate SFM values for HSS and carbide.

**Q: What about dwell at depth for blind holes?**

A: Blind holes get a 0.5-1.0 second dwell at depth to let the drill clean up the bottom before retract. Without dwell, the last chip can smear on the bottom and leave a rough finish. Through holes do not need dwell. The calculator recommends 0.5 s for blind and 1.0 s for deep holes.

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Source: https://vastcalc.com/calculators/physics/drill-feed-and-speed
Category: Physics
Last updated: 2026-04-08