Calculate Cutting Speed, Spindle RPM and CNC Feed Rate
Convert cutting speed, spindle RPM, feed per tooth, chip load, feed per revolution, and table feed for CNC milling and drilling. Switch between metric and imperial units, compare calculated parameters, and check machine speed and feed limits before machining.
CNC Speed and Feed Calculator: Milling and Drilling
Convert cutting speed, spindle speed, chip load, feed per revolution and linear feed. Units and entered values stay synchronized when you change calculation mode.
Use effective cutting diameter at engagement, if different from nominal.
Count teeth actually engaged in milling feed calculation.
Speeds and Feeds Calculator Results
Calculated values are mathematical conversions of your inputs, not verified cutting-data recommendations.
Milling Speeds and Feeds Calculator: Formulas
A spindle speed calculator determines RPM from cutting speed and effective cutter diameter. A cutting speed calculator reverses this equation when RPM is known. For a surface feet per minute calculator, the same peripheral-speed relationship uses inch diameter and a factor of 12.
- Metric: RPM = 1000 × Vc ÷ (π × Dmm)
- Imperial: RPM = 12 × SFM ÷ (π × Din)
- Table feed Vf = RPM × number of effective teeth × fz
- Feed per revolution fn = Vf ÷ RPM
- Feed per tooth fz = Vf ÷ (RPM × teeth)
The cnc feed rate calculator uses actual spindle speed and chip load to determine table feed. The feed per tooth calculator and chip load calculator both express fz for milling. The end mill feed rate calculator must use the correct engaged tooth count, not an assumed flute count.
Confirm milling speeds, chip load, and effective tooth engagement against the cutting tool manufacturer’s recommendations for the exact tool, material, setup, and cutting conditions.
Drilling Speed and Feed Calculator: Formula Notes
Drilling mode uses drill diameter, cutting speed or RPM, and feed per revolution or linear feed. The feed per revolution calculator uses fn = Vf ÷ RPM. Unlike milling, the tool does not present drilling feed as an end-mill chip load per tooth.
The sfm to rpm calculator supports inch-diameter inputs and SFM units. The rpm calculator for milling uses the effective cutting diameter at the current engagement, which can differ from nominal for some cutter geometries.
For cnc aluminum speeds and feeds, select the material family only as a project note. Actual Vc and fz depend on alloy and temper, cutter substrate, coatings, engagement, workholding and coolant. Confirm supplier cutting data before machining.
For drilling, validate chip evacuation, hole depth, coolant delivery, drill geometry, breakthrough conditions and machine limits. This tool does not compute axial thrust, torque, power, chip-thinning compensation or peck cycles.
Check the drill manufacturer’s application data for the exact drill diameter, grade, depth-to-diameter ratio, coolant method, and workpiece material before selecting production parameters.
CNC Feeds and Speeds Calculator FAQ
How to calculate spindle RPM?
For metric cutting speed in m/min and effective diameter in millimeters, RPM = (1000 × Vc)/(π × D). For SFM and inch diameter, RPM = (12 × SFM)/(π × D). Check spindle limits and actual cutting diameter.
What is feed per tooth?
Feed per tooth (fz) is the programmed linear advance for each effective cutting edge during one revolution in a milling operation. It is usually shown as mm/tooth or inch/tooth.
What is chip load in milling?
Chip load normally means feed per tooth, but actual chip thickness also depends on radial engagement, entering angle, toolpath and cutter geometry. This basic calculator does not perform chip-thinning corrections.
Can I convert a known table feed into chip load?
Yes. Choose Table feed as the known feed input. In milling mode, fz = table feed/(RPM × effective teeth). Drilling mode reports feed per revolution instead.
How to Check Your Cutting Parameters
Enter the effective tool diameter, cutting speed or spindle RPM, and one feed basis. Review the converted results against machine RPM/feed limits. Copy the parameter summary for an internal process review, then verify it against tool-specific cutting recommendations.
This cnc speed and feed calculator does not select safe cutting conditions automatically. For difficult materials, long overhang, thin walls or aggressive engagement, engineering trials and cutter-specific recommendations may require lower parameters.
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