CNC Speeds and Feeds Calculator

Free online tool for calculating cutting speed (Vc), spindle speed (RPM), feed rate (F), and material removal rate (MRR). Works for turning, milling, drilling, and boring with carbide insert, HSS, ceramic, and CBN tooling.

⚡ Instant 🔧 Carbide / HSS / CBN 🌍 Metric + Imperial 🏭 ISO 3685 Standard

Speeds and Feeds Calculator

Spindle Speed (N)
—RPM
Cutting Speed (Vc)
—m/min
Feed Rate (F)
—mm/min
Feed per Rev (f)
—mm/rev
MRR
—cm³/min
Power (est.)
—kW
—
—

Recommended Cutting Speeds by Material

Reference values for carbide insert tooling with coolant. Adjust ±20% based on machine rigidity, insert geometry, and toolholder clamping stability.

Workpiece Material Hardness Vc (m/min) fn (mm/tooth) Application
Aluminum 6061 / 7075 95–110 HB 300–800 0.08–0.30 Aerospace, automotive, fixtures
Cast Aluminum (high Si) 80–120 HB 150–350 0.05–0.20 Engine blocks, transmission housings
Mild Steel (<30 HRC) 120–180 HB 120–250 0.10–0.30 Shafts, gears, brackets
Alloy Steel (30–40 HRC) 180–380 HB 80–180 0.08–0.25 Mold bases, machinery parts
Hardened Steel (40–55 HRC) 380–560 HB 50–100 0.05–0.15 Molds, dies (use CBN/ceramic)
Stainless Steel 304 / 316 150–200 HB 80–180 0.08–0.20 Medical, food, marine
Cast Iron (gray/ductile) 150–300 HB 80–200 0.10–0.30 Engine blocks, pump housings
Titanium Ti-6Al-4V 32–38 HRC 30–60 0.05–0.15 Aerospace, medical implants
Inconel 718 / Superalloy 36–44 HRC 20–45 0.04–0.10 Turbine blades, aerospace
Brass / Copper 50–100 HB 200–500 0.05–0.25 Plumbing, electrical
Engineering Plastic (PEEK, POM) — 100–500 0.05–0.20 Aerospace, medical
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BEYOND & OYYU carbide inserts with CVD/PVD coating — direct from Hangzhou factory, 3–7 day DHL worldwide.
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What Is a Speeds and Feeds Calculator?

A CNC speeds and feeds calculator computes the four critical machining parameters — cutting speed (Vc), spindle speed (N, RPM), feed rate (F), and material removal rate (MRR) — from a small set of inputs: tool diameter, workpiece material, tool material, and operation type. These four numbers determine tool life, surface finish, machining time, and ultimately part cost.

Setting them correctly is the difference between a tool that lasts 100 parts and one that lasts 10,000. This calculator uses the ISO 3685 standard formulas and includes Vc presets for 11 common workpiece materials ranging from aluminum to Inconel.

How to Use This Calculator

  1. Select your operation — turning, milling, drilling, or boring.
  2. Choose the workpiece material — match it to your actual stock.
  3. Pick the tool material — carbide for general use, HSS for hand tooling, ceramic/CBN for hardened steel above 55 HRC.
  4. Enter tool diameter (D) in mm.
  5. Number of teeth (Z) and feed per tooth (fn) auto-populated with safe starting values.
  6. Click Calculate to get instant results.

The Four Key Formulas

1. Cutting Speed (Vc) — m/min

Vc = (π × D × N) / 1000

Surface speed at the tool edge. Determined by tool-workpiece material pair, independent of spindle RPM.

2. Spindle Speed (N) — RPM

N = (Vc × 1000) / (π × D)

3. Feed Rate (F) — mm/min

Turning: F = N × f   |   Milling/Drilling: F = N × fn × Z

4. Material Removal Rate (MRR) — cm³/min

Turning: MRR = ap × f × Vc   |   Milling: MRR = ap × ae × F / 1000

Material-Specific Machining Tips

Aluminum (6061 / 7075)

Forgiving: high Vc (300–800 m/min), aggressive feeds. Use sharp uncoated or PCD tooling.

Stainless Steel (304 / 316)

Work-hardening. Use coated carbide (AlTiN or TiAlN), moderate Vc (80–180 m/min), and plenty of coolant.

Titanium (Ti-6Al-4V)

Low thermal conductivity. Low Vc (30–60 m/min), high-pressure coolant, sharp tools only.

Hardened Steel (>55 HRC)

Switch to ceramic or CBN. Vc 100–200 m/min for CBN. Never interrupt the cut.

Common Mistakes to Avoid

  • Coated inserts can take 30–50% higher Vc than uncoated.
  • Long, thin toolholders limit achievable Vc more than insert grade.
  • For turning, use insert IC (inscribed circle), not corner radius.
  • Light finishing passes can run 30% faster than roughing.
  • Dry machining: reduce Vc by 20–30% vs flood coolant.

Frequently Asked Questions

What is the difference between cutting speed (Vc) and spindle speed (RPM)?
Cutting speed is the linear speed at which the tool edge moves through the material (m/min). Spindle speed is how fast the tool rotates (RPM). Related by: Vc = (π × D × N) / 1000.
What happens if cutting speed is too high?
The tool edge overheats, causing rapid crater wear, plastic deformation, and premature failure. Work-hardening occurs in stainless and titanium.
What happens if cutting speed is too low?
Built-up edge forms, causing poor surface finish, vibration, and tool chipping. Cycle time increases unnecessarily.
Why do manufacturers list Vc as a range?
The range accounts for insert grade, tool geometry, depth of cut, workpiece hardness, coolant type, and machine rigidity. Start in the middle and adjust based on chip color and tool wear.
Is this calculator suitable for hobbyists / small CNC routers?
Yes. For hobby-grade routers that top out at 12,000 RPM, choose a smaller tool diameter or accept lower Vc. The calculator will show you the RPM needed.

About BEYOND & OYYU

BEYOND and OYYU are precision cutting tool brands from Super Industrial Trading Co., Ltd, a Hangzhou, China-based manufacturer with 13+ years of OEM/ODM experience for Mitsubishi, Kyocera, Tungaloy, Sandvik, Sumitomo, and Korloy specifications. All products ship with HS Code 8209 documentation for international customs clearance and are backed by 3–7 day DHL worldwide delivery.