# Feeds and Speeds Calculator

Free feeds and speeds calculator for CNC milling, drilling, and turning. Enter tool diameter, material, and flutes to get RPM, feed rate, chip load, and SFM. Supports imperial and metric.

## What this calculates

A feeds and speeds calculator turns a target surface cutting speed and chip load into the two machine inputs you actually program: spindle RPM and feed rate. This calculator handles milling (end mill or face mill), drilling, and turning on a lathe, and works for any tool material (HSS or carbide) and a broad library of workpiece materials including aluminum, mild steel, stainless, titanium, and plastic.

## Inputs

- **Operation** — options: Milling (end mill, face mill), Drilling, Turning (lathe) — Pick the machining operation. Milling and drilling use IPM, turning uses IPR.
- **Tool or Workpiece Diameter** (in) — min 0.001 — Cutter diameter for milling or drilling. For turning, enter the workpiece diameter being cut.
- **Workpiece Material** — options: Aluminum (600/1500 SFM), Mild Steel / Low Carbon (100/350 SFM), Alloy Steel / 4140 (70/250 SFM), Stainless Steel (60/200 SFM), Cast Iron (80/250 SFM), Brass (250/500 SFM), Bronze (150/350 SFM), Copper (200/500 SFM), Titanium (40/120 SFM), Plastic / Delrin (800/2000 SFM) — Material of the workpiece. SFM values shown as HSS/carbide baselines.
- **Tool Material** — options: HSS (high-speed steel), Carbide (solid or insert) — Carbide tools run 2-5x faster than HSS in most materials.
- **Flutes or Teeth** — min 1, max 16 — Number of cutting edges. For drills use 2. End mills are 2-4 flute for aluminum, 3-5 for steel.
- **Chip Load Override (IPT)** (in/tooth) — min 0 — Optional. Enter a specific chip load per tooth. Leave at 0 to use a material/diameter default.
- **Depth of Cut** (in) — min 0 — Axial depth of cut (milling) or feed depth. Used for MRR estimate.

## Outputs

- **Spindle Speed** (RPM) — Spindle RPM from SFM / (pi x D / 12).
- **Cutting Speed** (SFM) — Surface feet per minute for the chosen material and tool material.
- **Chip Load per Tooth** (IPT) — Feed per tooth (IPT) used for the feed rate calculation.
- **Feed Rate** — formatted as text — IPM for milling and drilling, IPR for turning.
- **Feed Rate (IPM)** (in/min) — Linear feed rate in inches per minute (milling and drilling).
- **Metal Removal Rate** (in^3/min) — Approximate MRR = DOC x tool_diameter x feed_rate (milling).

## Details

The core feeds and speeds formulas

Every feeds and speeds calculator reduces to two equations from the Machinery's Handbook:

  - RPM = (SFM x 12) / (pi x D) where SFM is surface feet per minute and D is the tool or workpiece diameter in inches.

  - Feed rate (IPM) = RPM x chip load x number of flutes for milling.

For drilling, feed rate is specified in inches per revolution (IPR) instead of per tooth, so the equation is feed rate = RPM x feed_per_rev. For turning on a lathe, feed is also IPR and the diameter in the RPM equation is the workpiece diameter being cut, not the tool.

Typical cutting speeds (SFM) by material

  
    MaterialHSS SFMCarbide SFM
  
  
    Aluminum6001500
    Mild steel100350
    Alloy steel (4140)70250
    Stainless steel60200
    Cast iron80250
    Brass250500
    Titanium40120
    Plastic (Delrin)8002000
  

Using this speeds and feeds calculator

Pick an operation (mill, drill, turn), enter your tool or workpiece diameter, select the material and tool material, and the calculator returns spindle RPM, feed rate, chip load per tooth, and an approximate metal removal rate. Inputs accept both imperial (inches) and metric (mm), so a feeds and speeds calculator metric setup is a single unit toggle away. Haas, Mazak, Okuma, and Tormach control macros all accept the same RPM and IPM values this calculator produces.

Drilling and turning

A drilling feeds and speeds calculator uses a feed per revolution scaled to drill diameter: typical values run 0.001 IPR for a 1/16 drill up to 0.015 IPR for a 3/4 drill in mild steel. For turning, feed per revolution of 0.005-0.010 IPR is normal for finishing, 0.015-0.020 IPR for roughing. The calculator falls back to these ranges automatically when you do not specify a chip load.

## Frequently Asked Questions

**Q: How do I calculate feeds and speeds for CNC machining?**

A: Use RPM = (SFM x 12) / (pi x D), where SFM is the surface feet per minute for your material and tool, and D is the tool diameter in inches. Then multiply RPM by chip load and number of flutes to get feed rate in inches per minute. This calculator does both steps for milling, drilling, and turning.

**Q: What SFM should I use for aluminum?**

A: Aluminum runs 600 SFM with HSS end mills and 1000-1500 SFM with carbide. For a 1/2 inch carbide end mill in aluminum at 1500 SFM, RPM = (1500 x 12) / (pi x 0.5) = 11,459 RPM, well within the range of most VMCs.

**Q: Does this feeds and speeds calculator support metric?**

A: Yes. Both tool diameter and depth of cut accept millimeters via the unit toggle, and RPM is unit-independent. If you prefer mm/min feed rates, multiply the IPM output by 25.4. A feeds and speeds calculator metric workflow works the same way as imperial once the input units are set.

**Q: Will these numbers work on a Haas VF or Mazak lathe?**

A: Yes, the physics do not care about the brand. A Haas feeds and speeds calculator, Mazak calculator, Okuma calculator, and Tormach calculator all produce the same RPM and IPM values because they all use the same SFM / chip load equations. Start at 80 percent of calculated feed for first-cut safety, then dial up based on chip color and sound.

**Q: What is the difference between feeds and speeds?**

A: Speed is how fast the cutting edge moves across the work (SFM, converted to spindle RPM by diameter). Feed is how fast the tool advances into the work (IPM for milling and drilling, IPR for turning). Together they determine chip thickness, cutting temperature, and tool life.

**Q: Why does carbide run so much faster than HSS?**

A: Carbide maintains hardness at much higher temperatures than high-speed steel, so it can handle the heat generated at higher SFM. In aluminum, carbide can run 2-3x faster than HSS. In steel, 3-4x. That is why production shops use carbide even for simple parts.

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Source: https://vastcalc.com/calculators/physics/feeds-and-speeds
Category: Physics
Last updated: 2026-04-08