CNC Feeds & Speeds Calculator

Precision-engineered parameters for routers and mills. Enter your setup below to get optimal RPM, feed rate, plunge rate, and chip load — instantly.

Machine Setup

Material

Tool Diameter (select preset or enter custom)

Flute Count

Operation Type

Machine Class / Rigidity

Depth of Cut (inches)

⏳

Awaiting Calculation

Configure your setup on the left, then hit Calculate.

Target Spindle Speed

—

RPM

Cutting Feed Rate

—

IPM

Plunge Rate

—

IPM

Chip Load / Tooth

—

inches/tooth

Material Removal Rate

—

in³/min

Stepover

—

inches

DOC Used

—

inches

📋 Copy to CAM Software

Run the calculator to generate CAM-ready parameters…

Recommended Tooling & Accessories

✦ As an Amazon Associate, MillCaliber earns from qualifying purchases. Affiliate links are marked with ★ and help keep this tool free.

Understanding Feeds & Speeds

Spindle RPM Formula

RPM is derived from the material's recommended Surface Feet per Minute (SFM) and your tool diameter. Harder materials require lower SFM.

RPM = (SFM × 3.82) / Ø (inches)

Cutting Feed Rate

Feed rate is the product of RPM, flute count, and the chip load per tooth. More flutes = faster feed at the same chip load.

Feed Rate = RPM × Flutes × IPT

Chip Load & Rigidity

Hobby belt-driven machines are scaled to 50–70% of rigid-machine chip loads to prevent bit breakage and chatter on flexible gantries.

Hobby Scale: 0.55× of rigid IPT

Plunge Rate Advisory

Straight plunges are limited to 30% of cutting feed. Use helical ramp entry whenever your CAM software supports it for longer tool life.

Plunge = Feed Rate × 0.30

Slotting vs Pocketing

Slotting (full-width) engages all flutes simultaneously — the most demanding cut. Reduce depth of cut by 30–40% vs pocketing passes.

Material Removal Rate

MRR measures cutting efficiency: Width × Depth × Feed Rate. Higher MRR means faster cycle times but greater spindle load.

MRR = WOC × DOC × Feed Rate