🤖 Computer Numerical Control

CNC Calculators

Four calculators covering feeds & speeds, material removal rate, cycle time, and theoretical surface finish Ra. Useful for milling, turning, and drilling operations. No login, no paywall.

Select Calculator

⚙️ Feeds & Speeds Calculator

Calculate RPM spindle speed and feed rate from cutting speed (Vc), tool diameter, number of flutes, and chip load. Works for milling and drilling.

Cutting Speed (Vc) *

m/min

From cutting data chart — see reference table below

Tool Diameter (D) *

Cutting diameter of end mill, drill bit, or turning insert tip

Number of Flutes / Teeth (z) *

flutes

2–4 for aluminium, 4–6 for steel

Chip Load (fz) *

mm/tooth

Typical: 0.01–0.15 mm for steel endmills

Tool Condition Factor

Fill in all required fields with valid values.

Spindle Speed (N)

—

RPM

⚙️

Table Feed Rate (Vf)
—
mm/min

Feed per Rev (fn)

—

mm/rev

Actual Vc (adjusted)

—

m/min

📐

Formula Used

G-code reference: Set spindle with S[RPM] and feed with F[mm/min]. Example: S2500 F350. Always verify against machine's max RPM and torque curve.

Cutting Speed Reference — Carbide Tools

Vc in m/min

Material	Roughing Vc	Finishing Vc	Typical fz (mm)
Aluminium alloy (6061)	200–400	400–800	0.05–0.15
Mild steel (EN8)	80–120	120–200	0.02–0.08
Alloy steel (EN36)	50–90	90–150	0.02–0.06
Stainless steel (304)	40–80	80–140	0.02–0.05
Cast iron (grey)	80–140	140–200	0.05–0.12
Hardened steel (HRC 45+)	30–60	60–100	0.01–0.04
Titanium alloy (Ti-6Al-4V)	30–60	50–80	0.03–0.08
Brass / Copper	100–200	200–350	0.05–0.15

📊 Material Removal Rate (MRR)

MRR is the volume of material removed per minute. Useful for estimating spindle power, cycle cost, and comparing roughing strategies.

Operation Type *

Feed Rate (Vf) *

mm/min

Table/workpiece feed rate

Radial Depth (ae) *

Stepover / width of cut

Axial Depth (ap) *

Depth of cut (axial)

Specific Cutting Force (kc)

Fill in all required fields with valid values.

Material Removal Rate

—

cm³/min

📊

MRR
—
mm³/min

Net Cutting Power

—

Add 30% for spindle losses

Cutting Force (Fc)

—

📐

Formula Used

⏱️ CNC Cycle Time Estimator

Estimate CNC machining cycle time from cutting passes, rapid moves, and tool changes. Useful for quoting, scheduling, and OEE calculations.

Total Cutting Length (L) *

Sum of all cutting tool paths

Cutting Feed Rate *

mm/min

Average feed rate during cutting passes

Rapid Traverse Distance

Air-cutting / positioning moves

Rapid Rate (G0)

mm/min

Machine max rapid. Typical: 8000–30000

Tool Changes

changes

ATC time ~4–8 s per change

Setup / Load-Unload Time

min

Operator fixture and workpiece time

Batch Quantity

parts

For batch time calculation

Fill in required cutting length and feed rate.

Cycle Time per Part

—

minutes

⏱️

Machining Time
—
min

Rapid + ATC Time

—

min

Batch Total

—

hours

📐

Breakdown

🔬 Theoretical Surface Finish Ra

Calculate theoretical peak-to-valley (Rt) and average roughness (Ra) from tool nose radius and feed per revolution. Valid for turning and finishing milling passes.

Tool Nose Radius (re) *

Turning insert nose radius: 0.2, 0.4, 0.8, 1.2 mm are standard

Feed per Revolution (fn) *

mm/rev

Turning finish: 0.05–0.2 mm/rev; roughing: 0.2–0.6 mm/rev

Workpiece Material

Cutting Speed (Vc)

m/min

Higher Vc generally gives better finish

Fill in tool nose radius and feed rate.

Theoretical Ra (average roughness)

—

µm

🔬

Peak-to-Valley (Rt)
—
µm

Ra / Rt Ratio

—

factor

Equivalent N Grade

—

ISO roughness grade

📐

Formula Used

⚠️ Note: This is the theoretical minimum Ra. Actual values are 1.5–2× higher due to vibration, tool wear, built-up edge, and workholding rigidity. Always verify with a surface profilometer on production samples.

ISO Roughness Grades — Ra Reference

ISO 1302 / ISO 4287

N Grade	Ra (µm)	Typical Process	Application
N12	50	Rough turning/milling	Unfinished casting marks
N11	25	Rough machining	Non-mating surfaces
N10	12.5	Coarse turning	General purpose
N9	6.3	Semi-finish turning	Clearance fits
N8	3.2	Finish turning/milling	General engineering
N7	1.6	Fine turning/milling	Press fits, bearing seats
N6	0.8	Fine turning / cylindrical grind	Running fits, bushings
N5	0.4	Fine grinding / honing	Precision bearings, seals
N4	0.2	Fine grinding / lapping	High-precision sliding fits

🤖

Vaibhav

Founder, TaskJunction

I built this because every machinist and process engineer reaches for a calculator when setting up a new job — and the good ones are either behind a paywall or buried in a Sandvik / Kennametal catalogue.

Whether you are on the shop floor dialling in a new endmill or quoting a job at 10 PM, you need quick numbers you can trust. This tool gives you that, free, with the formula shown so you understand what is happening.

No login. No email. No nonsense. Just the numbers you need to get your parts right the first time.

Vaibhav

[email protected]