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CNC Speeds & Feeds Calculator

Convert a tool's recommended cutting speed and chip load into spindle RPM and table feed rate for milling or drilling.

Spindle speed
1,910 RPM
Feed rate
611.2 mm/min
Feed per revolution
0.32 mm/rev

How it works

Spindle speed comes from the tool's recommended cutting (surface) speed Vc and its diameter, since Vc is just the linear speed of a point on the tool's edge tracing out a circle: RPM = (Vc × 1000) ÷ (π × D), with Vc in m/min and D in mm. Feed rate is then how fast the table has to advance so each flute removes the intended chip load once per revolution: feed rate = RPM × number of flutes × chip load. Verified via web search against Kennametal's own Speeds and Feeds Calculator and CNCCookbook's Feeds and Speeds guide, reproducing Kennametal's own worked examples (60 m/min on a 10mm end mill → 1,910 RPM; 5,000 RPM with a 4-flute, 0.08mm chip load → 1,600 mm/min) exactly.

This calculator only converts a cutting speed and chip load you already have into RPM and feed rate — it can't supply those two numbers itself. Recommended surface speeds and chip loads vary by tool material and coating, workpiece material, and machine rigidity, and are published in your tool manufacturer's own speeds-and-feeds charts, not a fact this site could hardcode without it going stale or being wrong for your specific tool.

FAQ

What cutting speed (Vc) should I enter for my material?

That depends on the tool material (HSS vs. carbide, coated or not) and the workpiece material (aluminum, mild steel, stainless, etc.) — your cutting tool's manufacturer publishes recommended Vc ranges for exactly this combination. This calculator converts whichever value you choose into spindle RPM; it doesn't look that value up for you.

What is chip load, and why does it matter?

Chip load (feed per tooth) is how far the workpiece advances during the time one cutting edge is engaged — effectively how thick a chip each flute removes per pass. Too low, and the edge rubs instead of cutting cleanly (causing heat and premature wear); too high, and the tool risks chipping or breaking. Like cutting speed, the right chip load range comes from the tool manufacturer's own charts for your specific tool diameter and material.

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